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June 20, 2024

Post-Exploitation Activities on PAN-OS Devices: A Network-Based Analysis

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20
Jun 2024
This blog investigates the network-based activity detected by Darktrace in compromises stemming from the exploitation of a vulnerability in Palo Alto Networks firewall devices, namely CVE-2024-3400.

Update:
Following the initial publication of this blog detailing exploitation campaigns utilizing the recently disclosed vulnerability, Darktrace analysts expanded the scope of the threat research investigation to identify potential earlier, pre-CVE disclosure, exploitation of CVE 2024-3400. While the majority of PAN-OS exploitation activity seen in the Darktrace customer base occurred after the public release of the CVE, Darktrace did also see tooling activity likely related to CVE-2024-3400 exploitation prior to the vulnerability's disclosure. Unlike the post-CVE-release exploitation activity, which largely reflected indiscriminate, opportunistic targeting of unpatched systems, these pre-CVE release activities likely represented selective targeting by more calculated actors.

Between March 26 and 28, Darktrace identified two Palo Alto firewall devices within the network of a public sector customer making HTTP GET requests utilizing both cURL and wget user agents, versions of which were seen in later compromise activity in April. The devices requested multiple shell script files (.sh) from rare external IP addresses. These IPs are likely associated with an operational relay box (ORB) network[1]. The connections also occurred without a specified hostname lookup, suggesting the IPs were hardcoded into process code or already cached through unexpected running processes. One of the destination IPs was later confirmed by Palo Alto Network’s Unit 42 as associated with exploitation of the PAN-OS vulnerability[2]. This observed activity closely resembles post-exploitation activity seen on affected firewall devices in mid-April. However, unlike the more disruptive and noisier follow-on exploitation activity seen in post-CVE-release incidents, the pre-CVE-release case observed by Darktrace appears to have been much more discreet, likely due to the relevant threat actor's desire to remain undetected.

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Introduction

Perimeter devices such as firewalls, virtual private networks (VPNs), and intrusion prevention systems (IPS), have long been the target of adversarial actors attempting to gain access to internal networks. However, recent publications and public service announcements by leading public institutions underscore the increased emphasis threat actors are putting on leveraging such products to initiate compromises.

A blog post by the UK National Cyber Security Center (NCSC) released in early 2024 notes that as improvements are made in the detection of phishing email payloads, threat actors have again begun re-focusing efforts to exploiting network edge devices, many of which are not secure by design, as a means of breach initiation.[i] As such, it comes as no surprise that new Common Vulnerabilities and Exposures (CVEs) are constantly discovered that exploit such internet-exposed systems.

Darktrace analysts frequently observe the impacts of such CVEs first through their investigations via Darktrace’s Security Operations Center (SOC). Beginning in April 2024, Darktrace’s SOC began handling alerts and customer requests for potential incidents involving Palo Alto Networks firewall devices.  Just days prior, external researchers publicly disclosed what would later be classified as PAN-OS CVE-2024-3400, a form of remote command execution vulnerability that affects several versions of Palo Alto Networks’ firewall operating system (PAN-OS), namely PAN-OS 11.1, 11.0 and 10.2. At the time, multiple Darktrace customers were unaware of the recently announced vulnerability.

The increase in observed SOC activity for Palo Alto firewall devices, coupled with the public announcement of the new CVE prompted Darktrace researchers to look for evidence of PAN-OS exploitation on customer networks. Researchers also focused on documenting post-exploitation activity from threat actors leveraging the recently disclosed vulnerability.

As such, this blog highlights the network-based behaviors involved in the CVE-2024-3400 attack chains investigated by Darktrace’s SOC and Threat Research teams. Moreover, this investigation also provides a deeper insight into the post-compromise activities of threat actors leveraging the novel CVE.  Such insights will not only prove relevant for cybersecurity teams looking to inhibit compromises in this specific instance, but also highlights general patterns of behavior by threat actors utilizing such CVEs to target internet-facing systems.

CVE-2024-3400

In mid-April 2024, the Darktrace SOC observed an uptick in activity involving recurring patterns of malicious activity from Palo Alto firewall appliances. In response to this trend, Darktrace initiated a Threat Research investigation into such activity to try and identify common factors and indicators across seemingly parallel events. Shortly before the Threat Research team opened their investigation, external researchers provided public details of CVE-2024-3400, a form of remote command execution vulnerability in the GlobalProtect feature on Palo Alto Network firewall devices running PAN-OS versions: 10.2, 11.0, and 11.1.[ii]

In their proof of concept, security researchers at watchTowr demonstrated how an attacker can pass session ID (SESSID) values to these PAN-OS devices to request files that do not exist. In response, the system creates a zero-byte file with root privileges with the same name.[iii] Log data is passed on devices running telemetry services to external servers through command line functionality.[iv] Given this functionality, external actors could then request non-existent files in the SESSID containing command parameters which then be interpreted by the command line functionality.[v] Although researchers first believed the exploit could only be used against devices running telemetry services, this was later discovered to be untrue.[vi]

As details of CVE-2024-3400 began to surface, Darktrace’s Threat Research analysts quickly identified distinct overlaps in the observed activity on specific customer deployments and the post-exploitation behavior reported by external researchers. Given the parallels, Darktrace correlated the patterns of activity observed by the SOC team to exploitation of the newly discovered vulnerability in PAN-OS firewall appliances.

Campaign Analysis

Between the April and May 2024, Darktrace identified four main themes of post-exploitation activity involving Palo Alto Network firewall devices likely targeted via CVE-2024-3400: exploitation validation, shell command and tool retrieval, configuration data exfiltration, and ongoing command and control through encrypted channels and application protocols.

1. Exploit Validation and Further Vulnerability Enumeration

Many of the investigated attack chains began with malicious actors using out-of-band application security testing (OAST) services such as Interactsh to validate exploits against Palo Alto firewall appliances. This exploit validation activity typically resulted in devices attempting to contact unusual external endpoints (namely, subdomains of ‘oast[.]pro’, ‘oast[.]live’, ‘oast[.]site’, ‘oast[.]online’, ‘oast[.]fun’, ‘oast[.]me’, and ‘g3n[.]in’) associated with OAST services such as Interactsh. These services can be used by developers to inspect and debug internet traffic, but also have been easily abused by threat actors.

While attempted connections to OAST services do not alone indicate CVE-2024-3400 exploitation, the prevalence of such activities in observed Palo Alto firewall attack chains suggests widespread usage of these OAST services to validate initial access methods and possibly further enumerate systems for additional vulnerabilities.

Figure 1: Model alert log details showcasing a PAN-OS device making DNS queries for Interactsh domain names in what could be exploit validation, and/or further host enumeration.

2. Command and Payload Transmission

The most common feature across analyzed incidents was HTTP GET requests for shell scripts and Linux executable files (ELF) from external IPs associated with exploitation of the CVE. These HTTP requests were frequently initiated using the utilities, cURL and wget. On nearly every device likely targeted by threat actors leveraging the CVE, Darktrace analysts highlighted the retrieval of shell scripts that either featured enumeration commands, the removal of evidence of compromise activity, or commands to retrieve and start binaries on the destination device.

a) Shell Script Retrieval

Investigated devices commonly performed HTTP GET requests to retrieve shell command scripts. Despite this commonality, there was some degree of variety amongst the retrieved payloads and their affiliation with certain command tools. Several distinct types of shell commands and files were identified during the analyzed breaches. For example, some firewall devices were seen requesting .txt files associated with both Sliver C2, whose malicious use has previously been investigated by Darktrace, and Cobalt Strike. The target URIs of devices’ HTTP requests for these files included, “36shr.txt”, “2.txt”, “bin.txt”, and “data.txt”.

More interestingly, though, was the frequency with which analyzed systems requested bash scripts from rare external IP addresses, sometimes over non-standard ports for the HTTP protocol. These bash scripts would feature commands usually for the recipient system to check for certain existing files and or running processes. If the file did not exist, the system would then use cURL or wget to obtain content from external sites, change the permissions of the file, and then execute, sending output to dev/null as a means of likely defense evasion. In some scripts, the system would first make a new folder, and change directories prior to acquiring external content. Additionally, some samples highlighted multiple attempts at enumeration of the host system.

Figure 2: Packet capture (PCAP) data highlighting the incoming shell scripts providing instructions to use cURL to obtain external content, change the permissions of the file to execute, and then run the binary using the credentials and details provided.
Figure 3: PCAP data highlighting a variation of a shell script seen in an HTTP response processed by compromised devices. The script provides instructions to make a directory, retrieve and execute external content, and to hide the output.

Not every retrieved file that was not explicitly a binary featured bash scripts. Model alerts on some deployments also included file masquerading attempts by threat actors, whereby the Palo Alto firewall device would request content with a misleading extension in the URI. In one such instance, the requested URI, and HTTP response header suggests the returned content is an image/png, but the actual body response featured configuration parameters for a new daemon service to be run on the system.

Figure 4: PCAP data indicating configuration details likely for a new daemon on an investigated host. Such HTTP body content differs from the image/png extension within the request URI and declared content type in the HTTP response header.

Bash scripts analyzed across customer deployments also mirrored those identified by external security teams. External researchers previously reported on a series of identifiable shell commands in some cases of CVE-2024-3400 exploitation analyzed by their teams. Commands frequently involved a persistence mechanism they later labeled as the “UPSTYLE” backdoor.[vii]  This python-based program operates by reading commands hidden in error logs generated by 404 requests to the compromised server. The backdoor interprets the requests and writes the output to CSS files on the device. In many cases, Darktrace’s Threat Research team noted clear parallels between shell commands retrieved via HTTP GET request with those directly involving UPSTYLE. There were also matches with some URI patterns identified with the backdoor and requests observed on Darktrace deployments.

Figure 5: HTTP response data containing shell commands potentially relating to the UPSTYLE backdoor.

The presence of these UPSTYLE-related shell commands in response to Palo Alto firewall devices’ HTTP requests provides further evidence for initial exploitation of the CVE. Many bash scripts in examined cases interacted with folders and files likely related to CVE-2024-3400 exploitation. These scripts frequently sought to delete contents of certain folders, such as “/opt/panlogs/tmp/device_telemetry/minute/*” where evidence of exploitation would likely reside. Moreover, recursive removal and copy commands were frequently seen targeting CSS files within the GlobalProtect folder, already noted as the vulnerable element within PAN-OS versions. This evidence is further corroborated by host-based forensic analysis conducted by external researchers.[viii]

Figure 6: PCAP data from investigated system indicating likely defense evasion by removing content on folders where CVE exploitation occurred.

b) Executable File Retrieval

Typically, following command processing, compromised Palo Alto firewall devices proceeded to make web requests for several unusual and potentially malicious files. Many such executables would be retrieved via processed scripts. While there a fair amount of variety in specific executables and binaries obtained, overall, these executables involved either further command tooling such as Sliver C2 or Cobalt Strike payloads, or unknown executables. Affected systems would also employ uncommon ports for HTTP connections, in a likely attempt to evade detection. Extensions featured within the URI, when visible, frequently noted ‘.elf’ (Linux executable) or ‘.exe’ payloads. While most derived hashes did not feature identifiable open-source intelligence (OSINT) details, some samples did have external information tying the sample to specific malware. For example, one such investigation featured a compromised system requesting a file with a hash identified as the Spark malware (backdoor) while another investigated case included a host requesting a known crypto-miner.

Figure 7: PCAP data highlighting compromised system retrieving ELF content from a rare external server running a simple Python HTTP server.
Figure 8: Darktrace model alert logs highlighting a device labeled “Palo Alto” making a HTTP request on an uncommon port for an executable file following likely CVE exploitation.

3. Configuration Data Exfiltration and Unusual HTTP POST Activity

During Darktrace’s investigations, there were also several instances of sensitive data exfiltration from PAN-OS firewall devices. Specifically, targeted systems were observed making HTTP POST requests via destination port 80 to rare external endpoints that OSINT sources associate with CVE-2024-3400 exploitation and activity. PCAP analysis of such HTTP requests revealed that they often contained sensitive configuration details of the targeted Palo Alto firewall devices, including the IP address, default gateway, domain, users, superusers, and password hashes, to name only a few. Threat actors frequently utilized Target URIs such as “/upload” in their HTTP POST requests of this multi-part boundary form data. Again, the User-Agent headers of these HTTP requests largely involved versions of cURL, typically 7.6.1, and wget.

Figure 9: PCAP datahighlighting Palo Alto Firewall device running vulnerable version of PAN-OSposting configuration details to rare external services via HTTP.
Figure 10: Model alert logs highlighting a Palo Alto firewall device performing HTTP POSTs to a rare external IP, without a prior hostname lookup, on an uncommon port using a URI associated with configuration data exfiltration across analyzed incidents
Figure 11: Examples of TargetURIs of HTTP POST requests involving base64 encoded IPs and potential dataegress.

4. Ongoing C2 and Miscellaneous Activity

Lastly, a smaller number of affected Palo Alto firewall devices were seen engaging in repeated beaconing and/or C2 communication via both encrypted and unencrypted protocols during and following the initial series of kill chain events. Such encrypted channels typically involved protocols such as TLS/SSL and SSH. This activity likely represented ongoing communication of targeted systems with attacker infrastructure. Model alerts typically highlighted unusual levels of repeated external connectivity to rare external IP addresses over varying lengths of time. In some investigated incidents, beaconing activity consisted of hundreds of thousands of connections over several days.

Figure 12:  Advanced search details highlighting high levels of ongoing external communication to endpoints associated with C2 infrastructure exploiting CVE-2024-3400.

Some beaconing activity appears to have involved the use of the WebSocket protocol, as indicated by the appearance of “/ws” URIs and validated within packet captures. Such connections were then upgraded to an encrypted connection.

Figure 13:  PCAP highlighting use of WebSocket protocol to engage in ongoing external connectivity to likely C2 infrastructure following CVE-2024-3400 compromise.

While not directly visible in all the deployments, some investigations also yielded evidence of attempts at further post-exploitation activity. For example, a handful of the analyzed binaries that were downloaded by examined devices had OSINT information suggesting a relation to crypto-mining malware strains. However, crypto-mining activity was not directly observed at this time. Furthermore, several devices also triggered model alerts relating to brute-forcing activity via several authentication protocols (namely, Keberos and RADIUS) during the time of compromise. This brute-force activity likely represented attempts to move laterally from the affected firewall system to deeper parts of the network.

Figure 14: Model alert logs noting repeated SSL connectivity to a Sliver C2-affiliated endpoint in what likely constitutes C2 connectivity.
Figure 15: Model alert logs featuring repeated RADIUS login failures from a compromised PAN-OS device using generic usernames, suggesting brute-force activity.

Conclusion

Between April and late May 2024, Darktrace’s SOC and Threat Research teams identified several instances of likely PAN-OS CVE-2024-3400 exploitation across the Darktrace customer base. The subsequent investigation yielded four major themes that categorize the observed network-based post-exploitation activity. These major themes were exploit validation activity, retrieval of binaries and shell scripts, data exfiltration via HTTP POST activity, and ongoing C2 communication with rare external endpoints. The insights shared in this article will hopefully contribute to the ongoing discussion within the cybersecurity community about how to handle the likely continued exploitation of this vulnerability. Moreover, this article may also help cybersecurity professionals better respond to future exploitation of not only Palo Alto PAN-OS firewall devices, but also of edge devices more broadly.

Threat actors will continue to discover and leverage new CVEs impacting edge infrastructure. Since it is not yet known which CVEs threat actors will exploit next, relying on rules and signatures for the detection of exploitation of such CVEs is not a viable approach. Darktrace’s anomaly-based approach to threat detection, however, is well positioned to robustly adapt to threat actors’ changing methods, since although threat actors can change the CVEs they exploit, they cannot change the fact that their exploitation of CVEs results in highly unusual patterns of activity.

Credit to Adam Potter, Cyber Analyst, Sam Lister, Senior Cyber Analyst

Appendices

Pre-CVE-Release IoCs

38.54[.]104[.]14/3.sh
154.223[.]16[.]34/1.sh
154.223[.]16[.]34/co.sh
38.54[.]104[.]14/

Indicators of Compromise

Indicator – Type – Description

94.131.120[.]80              IP             C2 Endpoint

94.131.120[.]80:53/?src=[REDACTED]=hour=root                  URL        C2/Exfiltration Endpoint

134.213.29[.]14/?src=[REDACTED]min=root             URL        C2/Exfiltration Endpoint

134.213.29[.]14/grep[.]mips64            URL        Payload

134.213.29[.]14/grep[.]x86_64             URL        Payload

134.213.29[.]14/?deer               URL        Payload

134.213.29[.]14/?host=IDS   URL        Payload

134.213.29[.]14/ldr[.]sh           URL        Payload

91ebcea4e6d34fd6e22f99713eaf67571b51ab01  SHA1 File Hash               Payload

185.243.115[.]250/snmpd2[.]elf        URL        Payload

23.163.0[.]111/com   URL        Payload

80.92.205[.]239/upload            URL        C2/Exfiltration Endpoint

194.36.171[.]43/upload            URL        C2/Exfiltration Endpoint

update.gl-protect[.]com          Hostname         C2 Endpoint

update.gl-protect[.]com:63869/snmpgp      URL        Payload

146.70.87[.]237              IP address         C2 Endpoint

146.70.87[.]237:63867/snmpdd         URL        Payload

393c41b3ceab4beecf365285e8bdf0546f41efad   SHA1 File Hash               Payload

138.68.44[.]59/app/r URL        Payload

138.68.44[.]59/app/clientr     URL        Payload

138.68.44[.]59/manage            URL        Payload

72.5.43[.]90/patch      URL        Payload

217.69.3[.]218                 IP             C2 Endpoint

5e8387c24b75c778c920f8aa38e4d3882cc6d306                  SHA1 File Hash               Payload

217.69.3[.]218/snmpd[.]elf   URL        Payload

958f13da6ccf98fcaa270a6e24f83b1a4832938a    SHA1 File Hash               Payload

6708dc41b15b892279af2947f143af95fb9efe6e     SHA1 File Hash               Payload

dc50c0de7f24baf03d4f4c6fdf6c366d2fcfbe6c       SHA1 File Hash               Payload

109.120.178[.]253:10000/data[.]txt                  URL        Payload

109.120.178[.]253:10000/bin[.]txt   URL        Payload

bc9dc2e42654e2179210d98f77822723740a5ba6                 SHA1 File Hash               Payload

109.120.178[.]253:10000/123              URL        Payload

65283921da4e8b5eabb926e60ca9ad3d087e67fa                 SHA1 File Hash               Payload

img.dxyjg[.]com/6hiryXjZN0Mx[.]sh                  URL        Payload

149.56.18[.]189/IC4nzNvf7w/2[.]txt                 URL        Payload

228d05fd92ec4d19659d71693198564ae6f6b117 SHA1 File Hash               Payload

54b892b8fdab7c07e1e123340d800e7ed0386600                 SHA1 File Hash               Payload

165.232.121[.]217/rules          URL        Payload

165.232.121[.]217/app/request          URL        Payload

938faec77ebdac758587bba999e470785253edaf SHA1 File Hash               Payload

165.232.121[.]217/app/request63   URL        Payload

165.232.121[.]217:4443/termite/165.232.121[.]217             URL        Payload

92.118.112[.]60/snmpd2[.]elf               URL        Payload

2a90d481a7134d66e8b7886cdfe98d9c1264a386                 SHA1 File Hash               Payload

92.118.112[.]60/36shr[.]txt   URL        Payload

d6a33673cedb12811dde03a705e1302464d8227f                 SHA1 File Hash               Payload

c712712a563fe09fa525dfc01ce13564e3d98d67  SHA1 File Hash               Payload

091b3b33e0d1b55852167c3069afcdb0af5e5e79 SHA1 File Hash               Payload

5eebf7518325e6d3a0fd7da2c53e7d229d7b74b6                  SHA1 File Hash               Payload

183be7a0c958f5ed4816c781a2d7d5aa8a0bca9f SHA1 File Hash               Payload

e7d2f1224546b17d805617d02ade91a9a20e783e                 SHA1 File Hash               Payload

e6137a15df66054e4c97e1f4b8181798985b480d SHA1 File Hash               Payload

95.164.7[.]33:53/sea[.]png    URL        Payload

95.164.7[.]33/rules     URL        Payload

95.164.7[.]33:53/lb64                URL        Payload

c2bc9a7657bea17792048902ccf2d77a2f50d2d7 SHA1 File Hash               Payload

923369bbb86b9a9ccf42ba6f0d022b1cd4f33e9d SHA1 File Hash               Payload

52972a971a05b842c6b90c581b5c697f740cb5b9                 SHA1 File Hash               Payload

95d45b455cf62186c272c03d6253fef65227f63a    SHA1 File Hash               Payload

322ec0942cef33b4c55e5e939407cd02e295973e                  SHA1 File Hash               Payload

6335e08873b4ca3d0eac1ea265f89a9ef29023f2  SHA1 File Hash               Payload

134.213.29[.]14              IP             C2 Endpoint

185.243.115[.]250       IP             C2 Endpoint

80.92.205[.]239              IP             C2 Endpoint

194.36.171[.]43              IP             C2 Endpoint

92.118.112[.]60              IP             C2 Endpoint

109.120.178[.]253       IP             C2 Endpoint

23.163.0[.]111                 IP             C2 Endpoint

72.5.43[.]90     IP             C2 Endpoint

165.232.121[.]217       IP             C2 Endpoint

8.210.242[.]112              IP             C2 Endpoint

149.56.18[.]189              IP             C2 Endpoint

95.164.7[.]33  IP             C2 Endpoint

138.68.44[.]59                 IP             C2 Endpoint

Img[.]dxyjg[.]com         Hostname         C2 Endpoint

Darktrace Model Alert Coverage

·      Anomalous Connection / New User Agent to IP Without Hostname

·      Device / New User Agent (triggered by pre-CVE-release activity)

·      Anomalous File / Script from Rare External Location (triggered by pre-CVE-release activity)

·      Anomalous File / Masqueraded File Transfer

·      Anomalous File / EXE from Rare External Location

·      Anomalous File / Multiple EXE from Rare External Locations

·      Anomalous File / Script and EXE from Rare External

·      Anomalous File / Suspicious Octet Stream Download

·      Anomalous File / Numeric File Download

·      Anomalous Connection / Application Protocol on Uncommon Port

·      Anomalous Connection / Posting HTTP to IP Without Hostname

·      Anomalous Connection / Multiple Failed Connections to Rare Endpoint

·      Anomalous Connection / Suspicious Self-Signed SSL

·      Anomalous Connection / Anomalous SSL without SNI to New External

·      Anomalous Connection / Multiple Connections to New External TCP Port

·      Anomalous Connection / Rare External SSL Self-Signed

·      Anomalous Server Activity / Outgoing from Server

·      Anomalous Server Activity / Rare External from Server

·      Compromise / SSH Beacon

·      Compromise / Beacon for 4 Days

·      Compromise / Sustained TCP Beaconing Activity To Rare Endpoint

·      Compromise / High Priority Tunnelling to Bin Services

·      Compromise / Sustained SSL or HTTP Increase

·      Compromise / Connection to Suspicious SSL Server

·      Compromise / Suspicious File and C2

·      Compromise / Large Number of Suspicious Successful Connections

·      Compromise / Slow Beaconing Activity To External Rare

·      Compromise / HTTP Beaconing to New Endpoint

·      Compromise / SSL or HTTP Beacon

·      Compromise / Suspicious HTTP and Anomalous Activity

·      Compromise / Beacon to Young Endpoint

·      Compromise / High Volume of Connections with Beacon Score

·      Compromise / Suspicious Beaconing Behaviour

·      Compliance / SSH to Rare External Destination

·      Compromise / HTTP Beaconing to Rare Destination

·      Compromise / Beaconing Activity To External Rare

·      Device / Initial Breach Chain Compromise

·      Device / Multiple C2 Model Breaches

MITRE ATTACK Mapping

Tactic – Technique

Initial Access  T1190 – Exploiting Public-Facing Application

Execution           T1059.004 – Command and Scripting Interpreter: Unix Shell

Persistence      T1543.002 – Create or Modify System Processes: Systemd Service

Defense Evasion           T1070.004 – Indicator Removal: File Deletion

Credential Access       T1110.001 – Brute Force: Password Guessing

Discovery           T1083 – File and System Discovery

T1057 – Process Discovery

Collection         T1005 – Data From Local System

Command and Control            

T1071.001 – Application Layer Protocol:  Web Protocols

T1573.002 – Encrypted Channel: Asymmetric Cryptography

T1571 – Non-Standard Port

T1105 – Ingress Tool Transfer

Exfiltration        

T1041 – Exfiltration over C2 Protocol

T1048.002 - Exfiltration Over Alternative Protocol: Exfiltration Over Asymmetric Encrypted Non-C2 Protocol

References

[1] https://cloud.google.com/blog/topics/threat-intelligence/china-nexus-espionage-orb-networks

[2] https://unit42.paloaltonetworks.com/cve-2024-3400/

[i]  https://www.ncsc.gov.uk/blog-post/products-on-your-perimeter

[ii] https://security.paloaltonetworks.com/CVE-2024-3400

[iii] https://labs.watchtowr.com/palo-alto-putting-the-protecc-in-globalprotect-cve-2024-3400/

[iv] https://labs.watchtowr.com/palo-alto-putting-the-protecc-in-globalprotect-cve-2024-3400/

[v] https://labs.watchtowr.com/palo-alto-putting-the-protecc-in-globalprotect-cve-2024-3400/

[vi] https://security.paloaltonetworks.com/CVE-2024-3400

[vii] https://www.volexity.com/blog/2024/04/12/zero-day-exploitation-of-unauthenticated-remote-code-execution-vulnerability-in-globalprotect-cve-2024-3400/

[viii] https://www.volexity.com/blog/2024/05/15/detecting-compromise-of-cve-2024-3400-on-palo-alto-networks-globalprotect-devices/

Inside the SOC
Darktrace cyber analysts are world-class experts in threat intelligence, threat hunting and incident response, and provide 24/7 SOC support to thousands of Darktrace customers around the globe. Inside the SOC is exclusively authored by these experts, providing analysis of cyber incidents and threat trends, based on real-world experience in the field.
Author
Adam Potter
Senior Cyber Analyst
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RansomHub revisited: New front-runner in the ransomware-as-a-service marketplace

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In a previous Inside the SOC blog, Darktrace investigated RansomHub and its growing impact on the threat landscape due to its use by the ShadowSyndicate threat group. Here, RansomHub is revisited with new insights on this ransomware-as-a-service (RaaS) platform that has rapidly gained traction among threat actors of late.

In recent months, Darktrace’s Threat Research team has noted a significant uptick in potential compromises affecting the fleet, indicating that RansomHub is becoming a preferred tool for cybercriminals.  This article delves into the increasing adoption of RansomHub, the tactics, techniques, and procedures (TTPs) employed by its affiliates, and the broader implications for organizations striving to protect their systems.

RansomHub overview & background

One notable threat group to have transitioned from ALPHV (BlackCat)-aligned operations to RansomHub-aligned operations is ScatteredSpider [1]. The adoption of RansomHub by ScatteredSpider and other threat actors suggests a possible power shift among threat groups, given the increasing number of cybercriminals adopting it, including those who previously relied on ALPHV’s malware code [2].

ALPHV was a RaaS strain used by cybercriminals to breach Change Healthcare in February 2024 [2]. However, there are claims that the ransom payment never reached the affiliate using ALPHV, leading to a loss of trust in the RaaS. Around the same time, Operation Cronos resulted in the shutdown of LockBit and the abandonment of its affiliates [2]. Consequently, RansomHub emerged as a prominent RaaS successor.

RansomHub targets

The RansomHub ransomware group has been observed targeting various sectors, including critical infrastructure, financial and government services, and the healthcare sector [4]. They use ransomware variants rewritten in GoLang to target both Windows and Linux systems [5]. RansomHub is known for employing double extortion attacks, encrypting data using “Curve25519” encryption [6].

RansomHub tactics and techniques

The attackers leverage phishing attacks and social engineering techniques to lure their victims. Once access is gained, they use sophisticated tools to maintain control over compromised networks and exploit vulnerabilities in systems like Windows, Linux, ESXI, and NAS.

In more recent RansomHub attacks, tools such as Atera and Splashtop have been used to facilitate remote access, while NetScan has been employed to discover and retrieve information about network devices [7].

External researchers have observed that RansomHub uses several legitimate tools, or a tactic known as Living-off-the-Land (LOTL), to carry out their attacks. These tools include:

  • SecretServerSecretStealer: A PowerShell script that allows for the decryption of passwords [1].
  • Ngrok: A legitimate reverse proxy tool that creates a secure tunnel to servers located behind firewalls, used by the group for lateral movement and data exfiltration.
  • Remmina: An open-source remote desktop client for POSIX-based operating systems, enabling threat actors to access remote services [1].

By using these legitimate tools instead of traditional malware, RansomHub can avoid detection and maintain a lower profile during their operations.

Darktrace’s Coverage of RansomHub

Darktrace’s Security Operations Center (SOC) detected several notable cases of likely RansomHub activity across the customer base in recent months. In all instances, threat actors performed network scanning and brute force activities.

During the investigation of a confirmed RansomHub attack in January 2025, the Darktrace Threat Research team identified multiple authentication attempts as attackers tried to retrieve valid credentials. It is plausible that the attackers gained entry to customer environments through their Remote Desktop (RD) web server. Following this, various RDP connections were made to pivot to other devices within the network.

The common element among the cases investigated was that, in most instances, devices were seen performing outgoing connections to splashtop[.]com, a remote access and support software service, after the scanning activity had occurred. On one customer network, following this activity, the same device was seen connecting to the domain agent-api[.]atera[.]com and IP 20.37.139[.]187, which are seemingly linked to Atera, a Remote Monitoring and Management (RMM) tool.

Model Alert Log of an affected device making connections to *atera[.]com.
Figure 1: Model Alert Log of an affected device making connections to *atera[.]com.

In a separate case, a Darktrace observed a device attempting to perform SMB scanning activity, trying to connect to multiple internal devices over port 445. Cyber AI Analyst was able to detect and correlate these individual connections into a single reconnaissance incident.

Similar connections to Remote Monitoring and Management (RMM) tools were also detected in a different customer environment, as alerted by Darktrace’s SOC. Unusual connections to Splashtop and Atera were made from the alerted device. Following this, the same device was observed sending a large volume of data over SSH Rclone to a rare external endpoint on the unusual port 448, triggered multiple models in Darktrace / NETWORK.

Advanced Search graph demonstrating the rarity of the  external IP 38.244.145[.]85  used for data exfiltration.
Figure 2: Advanced Search graph demonstrating the rarity of the  external IP 38.244.145[.]85  used for data exfiltration.
Model Alert Log displaying information related to the suspicious IP, including the port used and its rarity for the network.
Figure 3: Model Alert Log displaying information related to the suspicious IP, including the port used and its rarity for the network.

In the cases observed, data exfiltration occurred alongside the encryption of files likely indicating double extortion tactics. In September 2024, the Darktrace’s Threat Research team identified a 6-digit alphanumeric additional extension similar to “.293ac3”. This case was closely linked to a RansomHub attack, which was also analyzed in a different blog post by Darktrace [8].

Event Log displaying the extension “.293ac3” being appended to encrypted files on an affected customer network.
Figure 4: Event Log displaying the extension “.293ac3” being appended to encrypted files on an affected customer network.

Conclusion

RansomHub exemplifies the evolving RaaS ecosystem, where threat actors capitalize on ready-made platforms to launch sophisticated attacks with ease. The activities observed highlight its growing popularity among cybercriminals. The analysis showed that the different attacks investigated followed a similar pattern of activity.

First, attackers perform reconnaissance activities, including widespread scanning from multiple devices and reverse DNS sweeps. They then use high-privileged credentials to pivot among devices and establish remote connections using RMM tools such as Atera. A common element among most attacks that reached the data encryption stage is the use of a 6-digit alphanumeric extension.

In all cases, Darktrace alerted on the unusual activities observed, creating not only model alerts but also Cyber AI Analyst incidents. Both Darktrace Security Operations Support and Darktrace Managed Threat Detection services provided 24/7 assistance to clients affected by RansomHub. The analyst team continued investigating these incidents, gathering data and IoCs seen in the RansomHub incidents, providing valuable insight and guidance throughout the process.

As RansomHub continues to gain traction, it serves as a stark reminder of the need for robust cybersecurity measures, proactive threat intelligence, and continued vigilance.

Credit to Maria Geronikolou (Cyber Analyst) and Nahisha Nobregas (Senior Cyber Analyst)

Appendices

Darktrace Model Detections

Network Reconnaissance

o   Device / Network Scan

o   Device / ICMP Address Scan

o   Device / RDP Scan

o   Device / Anomalous LDAP Root Searches

o   Anomalous Connection / SMB Enumeration

o   Device / Spike in LDAP Activity

o   Device / Suspicious Network Scan Activity

Lateral Movement

o   Device / Multiple Lateral Movement Model Alerts

o   Device / Increase in New RPC Services

o   Device / New or Uncommon WMI Activity

o   Device / Possible SMB/NTLM Brute Force

o   Device / SMB Session Brute Force (Non-Admin)

o   Device / Anomalous NTLM Brute Force

o   Compliance / Default Credential Usage

o   Compliance / Outgoing NTLM Request from DC

C2 Activity

o   Anomalous Server Activity / Outgoing from Server

o   Anomalous Connection / Multiple Connections to New External TCP Port

o   Unusual Activity / Unusual External Activity

o   Compliance / Remote Management Tool On Server

Data Exfiltration

o   Unusual Activity / Enhanced Unusual External Data Transfer

o   Anomalous Connection / Outbound SSH to Unusual Port

o   Compliance / SSH to Rare External Destination

o   Unusual Activity / Unusual External Data to New Endpoint

o   Unusual Activity / Unusual External Data Transfer

o   Attack Path Modelling / Unusual Data Transfer on Critical Attack Path

o   Compliance / Possible Unencrypted Password File On Server

Autonomous Response Models

-       Antigena / Network / Significant Anomaly / Antigena Significant Anomaly from Client Block

-       Antigena/Network/Insider Threat/Antigena SMB Enumeration Block

-       Antigena / Network / Significant Anomaly / Antigena Alerts Over Time Block

-       Antigena / Network / Significant Anomaly / Antigena Controlled and Model Alert

List of Indicators of Compromise (IoCs)

o   38.244.145[.]85

o   20.37.139[.]187 agent-api.atera[.]com

o   108.157.150[.]120 ps.atera[.]com

o   st-v3-univ-srs-win-3720[.]api[.]splashtop[.]com

MITRE ATT&CK Mapping

  • RECONNAISSANCE T1592.004
  • RECONNAISSANCE T1595.002
  • DISCOVERY T1046
  • DISCOVERY T1083
  • DISCOVERY T1135
  • DISCOVERY T1018
  • INITIAL ACCESS T1190
  • CREDENTIAL ACCESS T1110
  • LATERAL MOVEMENT T1210
  • COMMAND AND CONTROL T1001
  • EXFILTRATION T1041
  • EXFILTRATION T1567.002

References

[1] https://www.guidepointsecurity.com/blog/worldwide-web-an-analysis-of-tactics-and-techniques-attributed-to-scattered-spider/

[2] https://www.theregister.com/2024/07/16/scattered_spider_ransom/

[3] https://krebsonsecurity.com/2024/03/blackcat-ransomware-group-implodes-after-apparent-22m-ransom-payment-by-change-healthcare/

[4] https://thehackernews.com/2024/09/ransomhub-ransomware-group-targets-210.html

[5] https://www.trendmicro.com/vinfo/us/security/news/ransomware-spotlight/ransomware-spotlight-ransomhub

[6] https://areteir.com/article/malware-spotlight-ransomhub-ransomware/
[7] https://www.security.com/threat-intelligence/ransomhub-knight-ransomware

[8] https://darktrace.com/blog/ransomhub-ransomware-darktraces-investigation-of-the-newest-tool-in-shadowsyndicates-arsenal

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About the author
Maria Geronikolou
Cyber Analyst

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February 6, 2025

Reimagining Your SOC: Unlocking a Proactive State of Security

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Part 1: How to Achieve Proactive Network Security

Part 2: Overcoming Alert Fatigue with AI-Led Investigations  

While the success of a SOC team is often measured through incident management effectiveness (E.g MTTD, MTTR), a true measure of maturity is the reduction of annual security incidents.

Organizations face an increasing number of alerts each year, yet the best SOC teams place focus on proactive operations which don’t reduce the threshold for what becomes an incident but targets the source risks that prevent them entirely.

Freeing up time to focus on cyber risk management is a challenge in and of itself, we cover this in the previous two blogs in this series (see above). However, when the time comes to manage risk, there are several challenges that are unique when compared to detection & response functions within cybersecurity.

Why do cyber risks matter?

While the volume of reported CVEs is increasing at an alarming rate[1], determining the criticality of each vulnerability is becoming increasingly challenging, especially when the likelihood and impact may be different for each organization. Yet vulnerabilities have stood as an important signpost in traditional security and mitigation strategies. Now, without clear prioritization, potentially severe risks may go unreported, leaving organizations exposed to significant threats.

Vulnerabilities also represent just one area of potential risks. Cyberattacks are no longer confined to a single technology type. They now traverse various platforms, including cloud services, email systems, and networks. As technology infrastructure continues to expand, so does the attack surface, making comprehensive visibility across all technology types essential for reducing risk and preventing multi-vector attacks.

However, achieving this visibility is increasingly difficult as infrastructure grows and the cyber risk market remains oversaturated. This visibility challenge extends beyond technology to include personnel and individual cyber hygiene which can still exacerbate broader cyberattacks whether malicious or not.

Organizations must adopt a holistic approach to preventative security. This includes improving visibility across all technology types, addressing human risks, and mobilizing swiftly against emerging security gaps.

“By 2026, 60% of cybersecurity functions will implement business-impact-focused risk assessment methods, aligning cybersecurity strategies with organizational objectives.” [2]

The costs of a fragmented approach

siloed preventative security measures or technologies
Figure 1: Organizations may have a combination of siloed preventative security measures or technologies in place

Unlike other security tools (like SIEM, NDR or SOAR) which contain an established set of capabilities, cyber risk reduction has not traditionally been defined by a single market, rather a variety of products and practices that each provide their own value and are overwhelming if too many are adopted. Just some examples include:

  • Threat and Vulnerability management: Leverages threat intelligence, CVEs and asset management; however, leaves teams with significant patching workflows, ignores business & human factors and is reliant on the speed of teams to keep up with each passing update.  
  • Continuous Controls Monitoring (CCM): Automatically audits the effectiveness of security controls based on industry frameworks but requires careful prioritization and human calculations to set-up effectively. Focuses solely on mobilization.
  • Breach and Attack Simulation (BAS): Automates security posture testing through mock scenarios but require previous prioritization and might not tell you how your specific technologies can be mitigated to reduce that risk.
  • Posture Management technologies: Siloed approaches across Cloud, SaaS, Data Security and even Gen AI that reactively assess misconfigurations and suggest improvements but with only industry frameworks to validate the importance of the risks.
  • Red teaming & Penetration testing: Required by several regulations including (GDPR, HIPPA, PCI, DSS), many organizations hire 'red teams' to perform real breaches in trusted conditions. Penetration tests reveal many flaws, but are not continuous, requiring third-party input and producing long to-do lists with input of broader business risk dependent on the cost of the service.
  • Third-party auditors: Organizations also use third-party auditors to identify assets with vulnerabilities, grade compliance, and recommend improvements. At best, these exercises become tick-box exercises for companies to stay in compliance with the responsibility still on the client to perform further discovery and actioning.

Many of these individual solutions on the market offer simple enhancement, or an automated version of an existing human security task. Ultimately, they lack an understanding of the most critical assets at your organization and are limited in scope, only working in a specific technology area or with the data you provide.

Even when these strategies are complete, implementation of the results require resources, coordination, and buy-in from IT, cybersecurity, and compliance departments. Given the nature of modern business structures, this can be labor and time intensive as responsibilities are shared by organizational segmentation spread across IT, governance, risk and compliance (GRC), and security teams.

Prioritize your true cyber risk with a CTEM approach

Organizations with robust security programs benefit from well-defined policies, standards, key risk indicators (KRIs), and operational metrics, making it easier to measure and report cyber risk accurately.

Implementing a framework like Gartner’s CTEM (Continuous Threat Exposure Management) can help governance by defining the most relevant risks to each organization and which specific solutions meet your improvement needs.

This five-step approach—scoping, discovery, prioritization, validation, and mobilization—encourages focused management cycles, better delegation of responsibilities and a firm emphasis on validating potential risks through technological methods like attack path modeling or breach and attack simulation to add credibility.

Implementing CTEM requires expertise and structure. This begins with an exposure management solution developed uniquely alongside a core threat detection and response offering, to provide visibility of an organization’s most critical risks, whilst linking directly to their incident-based workflows.

“By 2026, organizations prioritizing their security investments, based on a continuous threat exposure management program, will realize a two-third reduction in breaches.” [3]

Achieving a proactive security posture across the whole estate

Unlike conventional tools that focus on isolated risks, Darktrace / Proactive Exposure Management breaks down traditional barriers. Teams can define risk scopes with full, prioritized visibility of the critical risks between: IT/OT networks, email, Active Directory, cloud resources, operational groups, (or even the external attack surface by integrating with Darktrace / Attack Surface Management).

Our innovative, AI-led risk discovery provides a view that mirrors actual attacker methodologies. It does this through advanced algorithms that determine risk based on business importance, rather than traditional device-type prioritization. By implementing a sophisticated damage assessment methodology, security teams don’t just prioritize via severity but instead, the inherent impact, damage, weakness and external exposure of an asset or user.

These calculations also revolutionize vulnerability management by combining industry standard CVE measurements with that organization-specific context to ensure patch management efforts are efficient, rather than an endless list.

Darktrace also integrates MITRE ATT&CK framework mappings to connect all risks through attack path modeling. This offers validation to our AI’s scoring by presenting real world incident scenarios that could occur across your technologies, and the actionable mitigations to mobilize against them.

For those human choke points, security may also deploy targeted phishing engagements. These send real but harmless email ‘attacks’ to test employee susceptibility, strengthening your ability to identify weak points in your security posture, while informing broader governance strategies.

Combining risk with live detection and response

Together, each of these capabilities let teams take the best steps towards reducing risk and the volume of incidents they face. However, getting proactive also sharpens your ability to handle live threats if they occur.  

During real incidents Darktrace users can quickly evaluate the potential impact of affected assets, create their own risk detections based on internal policies, strengthen their autonomous response along critical attack paths, or even see the possible stage of the next attack.

By continually ingesting risk information into live triage workflows, security teams will develop a proactive-first mindset, prioritizing the assets and alerts that have the most impact to the business. This lets them utilize their resource in the most efficient way, freeing up even more time for risk management, mitigation and ensuring continuity for the business.

Whether your organization is laying the foundation for a cybersecurity program or enhancing an advanced one, Darktrace’s self-learning AI adapts to your needs:

  • Foundational stage: For organizations establishing visibility and automating detection and response.
  • Integrated stage: For teams expanding coverage across domains and consolidating tools for simplicity.
  • Proactive stage: For mature security programs enhancing posture with vulnerability management and risk prioritization.

The Darktrace ActiveAI Security Platform empowers security teams to adopt a preventative defense strategy by using Cyber AI Analyst and autonomous response to fuel quicker triage, incident handling and give time back for proactive efforts designed around business impact. The platform encapsulates the critical capabilities that help organizations be proactive and stay ahead of evolving threats.

darktrace proactive exposure management solution brief reduce risk cyber risk

Download the solution brief

Maximize security visibility and reduce risk:

  • Unify risk exposure across all technologies with AI-driven scoring for CVEs, human communications, and architectures.
  • Gain cost and ROI insights on CVE risks, breach costs, patch latency, and blind spots.
  • Strengthen employee awareness with targeted phishing simulations and training.
  • Align proactive and reactive security by assessing device compromises and prevention strategies.
  • Reduce risk with tailored guidance that delivers maximum impact with minimal effort.

Take control of your security posture today. Download here!

References

[1] https://nvd.nist.gov/vuln/search, Search all, Statistics, Total matches By Year 2023 against 2024

[2] https://www.gartner.com/en/documents/5598859

[3] https://www.gartner.com/en/articles/gartner-top-10-strategic-technology-trends-for-2024

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About the author
Gabriel Few-Wiegratz
Product Marketing Manager, Exposure Management and Incident Readiness
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