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Inside the SOC

[Part 1] Analysis of a Raccoon Stealer v1 Infection

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07
Nov 2022
07
Nov 2022
Darktrace’s SOC team observed a fast-paced compromise involving Raccoon Stealer v1. See which steps the Raccoon Stealer v1 took to extract company data!

Introduction

Towards the end of March 2022, the operators of Raccoon Stealer announced the closure of the Raccoon Stealer project [1]. In May 2022, Raccoon Stealer v2 was unleashed onto the world, with huge numbers of cases being detected across Darktrace’s client base. In this series of blog posts, we will follow the development of Raccoon Stealer between March and September 2022. We will first shed light on how Raccoon Stealer functioned before its demise, by providing details of a Raccoon Stealer v1 infection which Darktrace’s SOC saw within a client network on the 18th March 2022. In the follow-up post, we will provide details about the surge in Raccoon Stealer v2 cases that Darktrace’s SOC has observed since May 2022.  

What is Raccoon Stealer?

The misuse of stolen account credentials is a primary method used by threat actors to gain initial access to target environments [2]. Threat actors have several means available to them for obtaining account credentials. They may, for example, distribute phishing emails which trick their recipients into divulging account credentials. Alternatively, however, they may install information-stealing malware (i.e, info-stealers) onto users’ devices. The results of credential theft can be devastating. Threat actors may use the credentials to gain access to an organization’s SaaS environment, or they may use them to drain users’ online bank accounts or cryptocurrency wallets. 

Raccoon Stealer is a Malware-as-a-Service (MaaS) info-stealer first publicized in April 2019 on Russian-speaking hacking forums. 

Figure 1: One of the first known mentions of Raccoon Stealer on a Russian-speaking hacking forum named ‘Hack Forums’ on the 13th April 2019

The team of individuals behind Raccoon Stealer provide a variety of services to their customers (known as ‘affiliates’), including access to the info-stealer, an easy-to-use automated backend panel, hosting infrastructure, and 24/7 customer support [3]. 

Once Raccoon Stealer affiliates gain access to the info-stealer, it is up to them to decide how to distribute it. Since 2019, affiliates have been observed distributing the info-stealer via a variety of methods, such as exploit kits, phishing emails, and fake cracked software websites [3]/[4]. Once affiliates succeed in installing Raccoon Stealer onto target systems, the info-stealer will typically seek to obtain sensitive information saved in browsers and cryptocurrency wallets. The info-stealer will then exfiltrate the stolen data to a Command and Control (C2) server. The affiliate can then use the stolen data to conduct harmful follow-up activities. 

Towards the end of March 2022, the team behind Raccoon Stealer publicly announced that they would be suspending their operations after one of their core developers was killed during the Russia-Ukraine conflict [5]. 

Figure 2: Raccoon Stealer resignation post on March 25th 2022

Recent details shared by the US Department of Justice [6]/[7] indicate that it was in fact the arrest, rather than the death, of a key Raccoon Stealer operator which led the Raccoon Stealer team to suspend their operations [8].  

The closure of the Raccoon Stealer project, which ultimately resulted from the FBI-backed dismantling of Raccoon Stealer’s infrastructure in March 2022, did not last long, with the completion of Raccoon Stealer v2 being announced on the Raccoon Stealer Telegram channel on the 17th May 2022 [9]. 

 

Figure 3: Telegram post about new version of Raccoon Stealer

In the second part of this blog series, we will provide details of the recent surge in Raccoon Stealer v2 activity. In this post, however, we will provide insight into how the old version of Raccoon Stealer functioned just before its demise, by providing details of a Raccoon Stealer v1 infection which occurred on the 18th March 2022. 

Attack Details

On the 18th March, at around 13:00 (UTC), a user’s device within a customer’s network was seen contacting several websites providing fake cracked software. 

Figure 4: The above figure — obtained from the Darktrace Event Log for the infected device — highlights its connections to cracked software websites such as ‘licensekeysfree[.]com’ and ‘hdlicense[.]com’ before contacting ‘lion-files[.]xyz’ and ‘www.mediafire[.]com’

The user’s attempt to download cracked software from one of these websites resulted in their device making an HTTP GET request with a URI string containing ‘autodesk-revit-crack-v2022-serial-number-2022’ to an external host named ‘lion-filez[.]xyz’

Figure 5: Screenshot from hdlicense[.]com around the time of the infection shows a “Download” button linking to the ‘lion-filez[.]xyz’ endpoint

The device’s HTTP GET request to lion-filez[.]xyz was immediately followed by an HTTPS connection to the file hosting service, www.mediafire[.]com. Given that threat actors are known to abuse platforms such as MediaFire and Discord CDN to host their malicious payloads, it is likely that the user’s device downloaded the Raccoon Stealer v1 sample over its HTTPS connection to www.mediafire[.]com.  

After installing the info-stealer sample, the user’s device was seen making an HTTP GET request with the URI string ‘/g_shock_casio_easy’ to 194.180.191[.]185. The endpoint responded to the request with data related to a Telegram channel named ‘G-Shock’.

Figure 6: Telegram channel ‘@g_shock_casio_easy’

The returned data included the Telegram channel’s description, which in this case, was a base64 encoded and RC4 encrypted string of characters [10]/[11]. The Raccoon Stealer sample decoded and decrypted this string of characters to obtain its C2 IP address, 188.166.49[.]196. This technique used by Raccoon Stealer v1 closely mirrors the espionage method known as ‘dead drop’ — a method in which an individual leaves a physical object such as papers, cash, or weapons in an agreed hiding spot so that the intended recipient can retrieve the object later on without having to come in to contact with the source. In this case, the operators of Raccoon Stealer ‘left’ the malware’s C2 IP address within the description of a Telegram channel. Usage of this method allowed the operators of Raccoon Stealer to easily change the malware’s C2 infrastructure.  

After obtaining the C2 IP address from the ‘G-Shock’ Telegram channel, the Raccoon Stealer sample made an HTTP POST request with the URI string ‘/’ to the C2 IP address, 188.166.49[.]196. This POST request contained a Windows GUID,  a username, and a configuration ID. These details were RC4 encrypted and base64 encoded [12]. The C2 server responded to this HTTP POST request with JSON-formatted configuration information [13], including an identifier string, URL paths for additional files, along with several other fields. This configuration information was also concealed using RC4 encryption and base64 encoding.  

Figure 7- Fields within the JSON-formatted configuration data [13]

In this case, the server’s response included the identifier string ‘hv4inX8BFBZhxYvKFq3x’, along with the following URL paths:

  • /l/f/hv4inX8BFBZhxYvKFq3x/77d765d8831b4a7d8b5e56950ceb96b7c7b0ed70
  • /l/f/hv4inX8BFBZhxYvKFq3x/0cb4ab70083cf5985b2bac837ca4eacb22e9b711
  • /l/f/hv4inX8BFBZhxYvKFq3x/5e2a950c07979c670b1553b59b3a25c9c2bb899b
  • /l/f/hv4inX8BFBZhxYvKFq3x/2524214eeea6452eaad6ea1135ed69e98bf72979

After retrieving configuration data, the user’s device was seen making HTTP GET requests with the above URI strings to the C2 server. The C2 server responded to these requests with legitimate library files such as sqlite3.dll. Raccoon Stealer uses these libraries to extract data from targeted applications. 

Once the Raccoon Stealer sample had collected relevant data, it made an HTTP POST request with the URI string ‘/’ to the C2 server. This posted data likely included a ZIP file (named with the identifier string) containing stolen credentials [13]. 

The observed infection chain, which lasted around 20 minutes, consisted of the following steps:

1. User’s device installs Raccoon Stealer v1 samples from the user attempting to download cracked software

2. User’s device obtains the info-stealer’s C2 IP address from the description text of a Telegram channel

3. User’s device makes an HTTP POST request with the URI string ‘/’ to the C2 server. The request contains a Windows GUID,  a username, and a configuration ID. The response to the request contains configuration details, including an identifier string and URL paths for additional files

4. User’s device downloads library files from the C2 server

5. User’s device makes an HTTP POST request with the URI string ‘/’ to the C2 server. The request contains stolen data

Darktrace Coverage 

Although RESPOND/Network was not enabled on the customer’s deployment, DETECT picked up on several of the info-stealer’s activities. In particular, the device’s downloads of library files from the C2 server caused the following DETECT/Network models to breach:

  • Anomalous File / Masqueraded File Transfer
  • Anomalous File / EXE from Rare External Location
  • Anomalous File / Zip or Gzip from Rare External Location
  • Anomalous File / EXE from Rare External Location
  • Anomalous File / Multiple EXE from Rare External Locations
Figure 8: Event Log for the infected device shows 'Anomalous File / Masqueraded File Transfer' model breach after the device's download of a library file from the C2 server

Since the customer was subscribed to the Darktrace Proactive Threat Notification (PTN) service, they were proactively notified of the info-stealer’s activities. The quick response by Darktrace’s 24/7 SOC team helped the customer to contain the infection and to prevent further damage from being caused. Having been alerted to the info-stealer activity by the SOC team, the customer would also have been able to change the passwords for the accounts whose credentials were exfiltrated.

If RESPOND/Network had been enabled on the customer’s deployment, then it would have blocked the device’s connections to the C2 server, which would have likely prevented any stolen data from being exfiltrated.

Conclusion

Towards the end of March 2022, the team behind Raccoon Stealer announced that they would be suspending their operations. Recent developments suggest that the arrest of a core Raccoon Stealer developer was responsible for this suspension. Just before the Raccoon Stealer team were forced to shut down, Darktrace’s SOC team observed a Raccoon Stealer infection within a client’s network. In this post, we have provided details of the network-based behaviors displayed by the observed Raccoon Stealer sample. Since these v1 samples are no longer active, the details provided here are only intended to provide historical insight into the development of Raccoon Stealer’s operations and the activities carried out by Raccoon Stealer v1 just before its demise. In the next post of this series, we will discuss and provide details of Raccoon Stealer v2 — the new and highly prolific version of Raccoon Stealer. 

Thanks to Stefan Rowe and the Threat Research Team for their contributions to this blog.

References

[1] https://twitter.com/3xp0rtblog/status/1507312171914461188

[2] https://www.gartner.com/doc/reprints?id=1-29OTFFPI&ct=220411&st=sb

[3] https://www.cybereason.com/blog/research/hunting-raccoon-stealer-the-new-masked-bandit-on-the-block

[4] https://www.cyberark.com/resources/threat-research-blog/raccoon-the-story-of-a-typical-infostealer

[5] https://www.bleepingcomputer.com/news/security/raccoon-stealer-malware-suspends-operations-due-to-war-in-ukraine/

[6] https://www.justice.gov/usao-wdtx/pr/newly-unsealed-indictment-charges-ukrainian-national-international-cybercrime-operation

[7] https://www.youtube.com/watch?v=Fsz6acw-ZJY

[8] https://riskybiznews.substack.com/p/raccoon-stealer-dev-didnt-die-in

[9] https://medium.com/s2wblog/raccoon-stealer-is-back-with-a-new-version-5f436e04b20d

[10] https://blog.cyble.com/2021/10/21/raccoon-stealer-under-the-lens-a-deep-dive-analysis/

[11] https://decoded.avast.io/vladimirmartyanov/raccoon-stealer-trash-panda-abuses-telegram/

[12] https://blogs.blackberry.com/en/2021/09/threat-thursday-raccoon-infostealer

[13] https://cyberint.com/blog/research/raccoon-stealer/

Appendices

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.
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What you need to know about the new SEC Cybersecurity rules

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17
Jul 2024

What is new in 2023 to SEC cybersecurity rules?

Form 8-K Item 1.05: Requiring the timely disclosure of material cybersecurity incidents.

Regulation S-K item 106: requiring registrants’ annual reports on Form 10-K to address cybersecurity risk management, strategy, and governance processes.

Comparable disclosures are required for reporting foreign private issuers on Forms 6-K and 20-F respectively.

What is Form 8-K Item 1.05 SEC cybersecurity rules?

Form 8-K Item 1.05 requires the following to be reported within four business days from when an incident is determined to be “material” (1), unless extensions are granted by the SEC under certain qualifying conditions:

“If the registrant experiences a cybersecurity incident that is determined by the registrant to be material, describe the material aspects of the nature, scope, and timing of the incident, and the material impact or reasonably likely material impact on the registrant, including its financial condition and results of operations.” (2, 3)

How does the SEC define cybersecurity incident?

Cybersecurity incident defined by the SEC means an unauthorized occurrence, or a series of related unauthorized occurrences, on or conducted through a registrant’s information systems that jeopardizes the confidentiality, integrity, or availability of a registrant’s information systems or any information residing therein. (4)

How can Darktrace assist in the process of disclosing incidents to the SEC?

Accelerate reporting

Darktrace’s Cyber AI Analyst generates automated reports that synthesize discrete data points potentially indicative of cybersecurity threats, forming reports that provide an overview of the evolution and impact of a threat.

Thus, when a potential threat is identified by Darktrace, AI Analyst can quickly compile information that organizations might include in their disclosure of an occurrence they determined to be material, including the following: incident timelines, incident events, incident summary, related model breaches, investigation process (i.e., how Darktrace’s AI conducted the investigation), linked incident events, and incident details. The figure below illustrates how Darktrace compiles and presents incident information and insights in the UI.

Overview of information provided in an ‘AI Analyst Report’ that could be relevant to registrants reporting a material cybersecurity incident to the SEC
Figure 1: Overview of information provided in an ‘AI Analyst Report’ that could be relevant to registrants reporting a material cybersecurity incident to the SEC

It should be noted that Instruction 4 to the new Form 8-K Item 1.05 specifies the “registrant need not disclose specific or technical information about its planned response to the incident or its cybersecurity systems, related networks and devices, or potential system vulnerabilities in such detail as would impede the registrant’s response or remediation of the incident” (5).

As such, the incident report generated by Darktrace may provide more information, including technical details, than is needed for the 8-K disclosure. In general, users should take appropriate measures to ensure that the information they provide in SEC reports meets the requirements outlined by the relevant regulations. Darktrace cannot recommend that an incident should be reported, nor report an incident itself.

Determine if a cybersecurity incident is material

Item 1.05 requires registrants to determine for themselves whether cybersecurity incidents qualify as ‘material’. This involves considerations such as ‘the nature scope and timing of the incident, and the material impact or reasonably likely material impact on the registrant, including its financial condition and results of operations.’

While it is up to the registrant to determine, consistent with existing legal standards, the materiality of an incident, Darktrace’s solution can provide relevant information which might aid in this evaluation. Darktrace’s Threat Visualizer user interface provides a 3-D visualization of an organization’s digital environment, allowing users to assess the likely degree to which an attack may have spread throughout their digital environment. Darktrace Cyber AI Analyst identifies connections among discrete occurrences of threatening activity, which can help registrants quickly assess the ‘scope and timing of an incident'.

Furthermore, in order to establish materiality it would be useful to understand how an attack might extend across recipients and environments. In the image below, Darktrace/Email identifies how a user was impacted across different platforms. In this example, Darktrace/Email identified an attacker that deployed a dual channel social engineering attack via both email and a SaaS platform in an effort to acquire login credentials. In this case, the attacker useding a legitimate SharePoint link that only reveals itself to be malicious upon click. Once the attacker gained the credentials, it proceeded to change email rules to obfuscate its activity.

Darktrace/Email presents this information in one location, making such investigations easier for the end user.

Darktrace/Email indicating a threat across SaaS and email
Figure 2: Darktrace/Email indicating a threat across SaaS and email

What is regulation S-K item 106 of the SEC cybersecurity rules?

The new rules add Item 106 to Regulation S-K requiring registrants to disclose certain information regarding their risk management, strategy, and governance relating to cybersecurity in their annual reports on Form 10-K. The new rules add Item 16K to Form 20-F to require comparable disclosure by [foreign private issuers] in their annual reports on Form 20-F. (6)

SEC cybersecurity rules: Risk management

Specifically, with respect to risk management, Item 106(b) and Item 16K(b) require registrants to describe their processes, if any, for assessing, identifying, and managing material risks from cybersecurity threats, as well as whether any risks from cybersecurity threats, including as a result of any previous cybersecurity incidents, have materially affected or are reasonably likely to materially affect them. The new rules include a non-exclusive list of disclosure items registrants should provide based on their facts and circumstances. (6)

SEC cybersecurity rules: Governance

With respect to governance, Item 106 and Item 16K require registrants to describe the board of directors’ oversight of risks from cybersecurity threats (including identifying any board committee or subcommittee responsible for such oversight) and management’s role in assessing and managing material risks from cybersecurity threats. (6)

How can Darktrace solutions aid in disclosing their risk management, strategy, and governance related to cybersecurity?

Impact scores

Darktrace End-to-End (E2E) leverages AI to understand the complex relationships across users and devices to model possible attack paths, giving security teams a contextual understanding of risk across their digital environments beyond isolated CVEs or CVSS scores. Additionally, teams can prioritize risk management actions to increase their cyber resilience through the E2E Advisory dashboard.

Attack paths consider:

  • Potential damages: Both the potential consequences if a given device was compromised and its immediate implications on other devices.
  • Exposure: Devices' level of interactivity and accessibility. For example, how many emails does a user get via mailing lists and from what kind of sources?
  • Impact: Where a user or asset sits in terms of the IT or business hierarchy and how they communicate with each other. Darktrace can simulate a range of possible outcomes for an uncertain event.
  • Weakness: A device’s patch latency and difficulty, a composite metric that looks at attacker MITRE methods and our own scores to determine how hard each stage of compromise is to achieve.

Because the SEC cybersecurity rules require “oversight of risks from cybersecurity threats” and “management’s role in assessing and managing material risks from cybersecurity threats” (6), the scores generated by Darktrace E2E can aid end-user’s ability to identify risks facing their organization and assign responsibilities to address those risks.

E2E attack paths leverage a deep understanding of a customer’ digital environment and highlight potential attack routes that an attacker could leverage to reach critical assets or entities. Difficulty scores (see Figure 5) allow security teams to measure potential damage, exposure, and impact of an attack on a specific asset or entity.

An example of an attack path in a digital environment
Figure 3: An example of an attack path in a digital environment

Automatic executive threat reports

Darktrace’s solution automatically produces Executive Threat Reports that present a simple visual overview of model breaches (i.e., indicators of unusual and threatening behaviors) and activity in the network environment. Reports can be customized to include extra details or restricted to high level information.

These reports can be generated on a weekly, quarterly, and yearly basis, and can be documented by registrants in relation to Item 106(b) to document parts of their efforts toward assessing, identifying, and managing material risks from cybersecurity threats.

Moreover, Cyber AI Analyst incident reports (described above) can be leveraged to document key details concerning significant previous incidents identified by the Darktrace solution that the registrant determined to be ‘material’.

While the disclosures required by Item 106(c) relate to the governance processes by which the board of directors, the management, and other responsible bodies within an organization oversee risks resulting from cybersecurity threats, the information provided by Darktrace’s Executive Threat Reports and Cyber AI Analyst incident reports can also help relevant stakeholders communicate more effectively regarding the threat landscape and previous incidents.

DISCLAIMER

The material above is provided for informational purposes only. This summary does not constitute legal or compliance advice, recommendations, or guidance. Darktrace encourages you to verify the contents of this summary with your own advisors.

References

  1. Note that the rule does not set forth any specific timeline between the incident and the materiality determination, but the materiality determination should be made without unreasonable delay.
  2. https://www.sec.gov/files/form8-k.pdf
  3. https://www.sec.gov/news/press-release/2023-139
  4. https://www.ecfr.gov/current/title-17/chapter-II/part-229
  5. https://www.sec.gov/files/form8-k.pdf
  6. https://www.sec.gov/corpfin/secg-cybersecurity
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Kendra Gonzalez Duran
Director of Technology Innovation

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Inside the SOC

Hashing out TA577: Darktrace’s Detection of NTLM Hash Theft

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09
Jul 2024

What is credential theft and how does it work?

What began as a method to achieve unauthorized access to an account, often driven by the curiosity of individual attackers, credentials theft become a key tactic for malicious actors and groups, as stolen login credentials can be abused to gain unauthorized access to accounts and systems. This access can be leveraged to carry out malicious activities such as data exfiltration, fraud, espionage and malware deployment.

It is therefore no surprise that the number of dark web marketplaces selling privileged credentials has increased in recent years, making it easier for malicious actors to monetize stolen credentials [1]. This, in turn, has created new opportunities for threat actors to use increasingly sophisticated tactics such as phishing, social engineering and credential stuffing in their attacks, targeting individuals, organizations and government entities alike [1].

Credential theft example

TA577 Threat Actor

TA577 is a threat actor known to leverage stolen credentials, also known as Hive0118 [2], an initial access broker (IAB) group that was previously known for delivering malicious payloads [2]. On March 4, 2024, Proofpoint reported evidence of TA577 using a new attack chain with a different aim in mind: stealing NT LAN Manager (NTLM) hashes that can be used to authenticate to systems without needing to know plaintext passwords [3].

How does TA577 steal credentials?

Proofpoint reported that this new attack chain, which was first observed on February 26 and 27, was made up of two distinct campaigns. The first campaign consisted of a phishing attack featuring tens of thousands of emails targeting hundreds of organizations globally [3]. These phishing emails often appeared as replies to previous messages (thread hijacking) and contained zipped HTML attachments that each contained a unique file hash, customized for each recipient [3]. These attached files also contained a HTTP Meta refresh function, which triggered an automatic connection to a text file hosted on external IP addresses running as SMB servers [3].

When attempting to access the text file, the server requires an SMB session authentication via NTLM. This session is initiated when a client sends an ‘SMB_COM_NEGOTIATE’ request to the server, which answers with a ‘SMB_COM_NEGOTIATE’ response.

The client then proceeds to send a ‘SMB_COM_SESSION_SETUP_ANDX’ request to start the SMB session setup process, which includes initiating the NTLM authentication process. The server responds with an ‘SMB_COM_SESSION_SETUP_ANDX’ response, which includes an NTLM challenge message [6].

The client can then use the challenge message and its own credentials to generate a response by hashing its password using an NTLM hash algorithm. The response is sent to the server in an ‘SMB_COM_SESSION_SETUP_ANDX’ request. The server validates the response and, if the authentication is successful, the server answers with a final ‘SMB_COM_SESSION_SETUP_ANDX’ response, which completes the session setup process and allows the client to access the file listed on the server [6].

What is the goal of threat actor TA577?

As no malware delivery was detected during these sessions, researchers have suggested that the aim of TA577 was not to deliver malware, but rather to take advantage of the NTLMV2 challenge/response to steal NTLM authentication hashes [3] [4]. Hashes stolen by attackers can be exploited in pass-the-hash attacks to authenticate to a remote server or service [4]. They can also be used for offline password cracking which, if successful, could be utilized to escalate privileges or perform lateral movement through a target network [4]. Under certain circumstances, these hashes could also permit malicious actors to hijack accounts, access sensitive information and evade security products [4].

The open-source toolkit Impacket, which includes modules for password cracking [5] and which can be identified by the default NTLM server challenge “aaaaaaaaaaaaaaaa”[3], was observed during the SMB sessions. This indicates that TA577 actor aim to use stolen credentials for password cracking and pass-the-hash attacks.

TA577 has previously been associated with Black Basta ransomware infections and Qbot, and has been observed delivering various payloads including IcedID, SystemBC, SmokeLoader, Ursnif, and Cobalt Strike [2].This change in tactic to follow the current trend of credential theft may indicate that not only are TA577 actors aware of which methods are most effective in the current threat landscape, but they also have monetary and time resources needed to create new methods to bypass existing detection tools [3].  

Darktrace’s Coverage of TA577 Activity

On February 26 and 26, coinciding with the campaign activity reported by Proofpoint, Darktrace/Email™ observed a surge of inbound emails from numerous suspicious domains targeting multiple customer environments. These emails consistently included zip files with seemingly randomly generated names, containing HTLM content and links to an unusual external IP address [3].

A summary of anomaly indicators seen for a campaign email sent by TA577, as detected by Darktrace/Email.
Figure 1: A summary of anomaly indicators seen for a campaign email sent by TA577, as detected by Darktrace/Email.
Details of the name and size of the .zip file attached to a campaign email, along with the Darktrace/Email model alerts triggered by the email.
Figure 2: Details of the name and size of the .zip file attached to a campaign email, along with the Darktrace/Email model alerts triggered by the email.

The URL of these links contained an unusually named .txt file, which corresponds with Proofpoint reports of the automatic connection to a text file hosted on an external SMB server made when the attachment is opened [3].

A link to a rare external IP address seen within a campaign email, containing an unusually named .txt file.
Figure 3: A link to a rare external IP address seen within a campaign email, containing an unusually named .txt file.

Darktrace identified devices on multiple customer networks connecting to external SMB servers via the SMB protocol. It understood this activity was suspicious as the SMB protocol is typically reserved for internal connections and the endpoint in question had never previously been observed on the network.

The Event Log of a ‘Compliance / External Windows Communication’ model alert showing a connection to an external SMB server on destination port 445.
Figure 4: The Event Log of a ‘Compliance / External Windows Communication’ model alert showing a connection to an external SMB server on destination port 445.
External Sites Summary highlighting the rarity of the external SMB server.
Figure 5: External Sites Summary highlighting the rarity of the external SMB server.
External Sites Summary highlightin that the SMB server is geolocated in Moldova.
Figure 6: External Sites Summary highlightin that the SMB server is geolocated in Moldova.

During these connections, Darktrace observed multiple devices establishing an SMB session to this server via a NTLM challenge/response, representing the potential theft of the credentials used in this session. During this session, some devices also attempted to access an unusually named .txt file, further indicating that the affected devices were trying to access the .txt file hosted on external SMB servers [3].

Packet captures (PCAPs) of these sessions show the default NTLM server challenge, indicating the use of Impacket, suggesting that the captured NTLM hashes were to be used for password cracking or pass-the-hash-attacks [3]

PCAP analysis showing usage of the default NTLM server challenge associated with Impacket.
Figure 7: PCAP analysis showing usage of the default NTLM server challenge associated with Impacket.

Conclusions

Ultimately, Darktrace’s suite of products effectively detected and alerted for multiple aspects of the TA577 attack chain and NTLM hash data theft activity across its customer base. Darktrace/Email was able to uncover the inbound phishing emails that served as the initial access vector for TA577 actors, while Darktrace DETECT identified the subsequent external connections to unusual external locations and suspicious SMB sessions.

Furthermore, Darktrace’s anomaly-based approach enabled it to detect suspicious TA577 activity across the customer base on February 26 and 27, prior to Proofpoint’s report on their new attack chain. This showcases Darktrace’s ability to identify emerging threats based on the subtle deviations in a compromised device’s behavior, rather than relying on a static list of indicators of compromise (IoCs) or ‘known bads’.

This approach allows Darktrace to remain one step ahead of increasingly adaptive threat actors, providing organizations and their security teams with a robust AI-driven solution able to safeguard their networks in an ever-evolving threat landscape.

Credit to Charlotte Thompson, Cyber Analyst, Anna Gilbertson, Cyber Analyst.

References

1)    https://www.sentinelone.com/cybersecurity-101/what-is-credential-theft/

2)    https://malpedia.caad.fkie.fraunhofer.de/actor/ta577

3)    https://www.proofpoint.com/us/blog/threat-insight/ta577s-unusual-attack-chain-leads-ntlm-data-theft

4)    https://www.bleepingcomputer.com/news/security/hackers-steal-windows-ntlm-authentication-hashes-in-phishing-attacks/

5)    https://pawanjswal.medium.com/the-power-of-impacket-a-comprehensive-guide-with-examples-1288f3a4c674

6)    https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-nlmp/c083583f-1a8f-4afe-a742-6ee08ffeb8cf

7)    https://www.hivepro.com/threat-advisory/ta577-targeting-windows-ntlm-hashes-in-global-campaigns/

Darktrace Model Detections

Darktrace/Email

·       Attachment / Unsolicited Archive File

·       Attachment / Unsolicited Attachment

·       Link / New Correspondent Classified Link

·       Link / New Correspondent Rare Link

·       Spoof / Internal User Similarities

Darktrace DETECT

·       Compliance / External Windows Communications

Darktrace RESPOND

·       Antigena / Network / Significant Anomaly / Antigena Breaches Over Time Block

IoCs

IoC - Type - Description

176.123.2[.]146 - IP address -Likely malicious SMB Server

89.117.2[.]33 - IP address - Likely malicious SMB Server

89.117.1[.]161 - IP address - Likely malicious SMB Server

104.129.20[.]167 - IP address - Likely malicious SMB Server

89.117.1[.]160 - IP address - Likely malicious SMB Server

85.239.33[.]149 - IP address - Likely malicious SMB Server

89.117.2[.]34 - IP address - Likely malicious SMB Server

146.19.213[.]36 - IP address - Likely malicious SMB Server

66.63.188[.]19 - IP address - Likely malicious SMB Server

103.124.104[.]76 - IP address - Likely malicious SMB Server

103.124.106[.]224 - IP address - Likely malicious SMB Server

\5aohv\9mn.txt - SMB Path and File - SMB Path and File

\hvwsuw\udrh.txt - SMB Path and File - SMB Path and File

\zkf2rj4\VmD.txt = SMB Path and File - SMB Path and File

\naams\p3aV.txt - SMB Path and File - SMB Path and File

\epxq\A.txt - SMB Path and File - SMB Path and File

\dbna\H.txt - SMB Path and File - SMB Path and File

MAGNAMSB.zip – Filename - Phishing Attachment

e751f9dddd24f7656459e1e3a13307bd03ae4e67 - SHA1 Hash - Phishing Attachment

OMNIS2C.zip  - Filename - Phishing Attachment

db982783b97555232e28d5a333525118f10942e1 - SHA1 Hash - Phishing Attachment

aaaaaaaaaaaaaaaa - NTLM Server Challenge -Impacket Default NTLM Challenge

MITRE ATT&CK Tactics, Techniques and Procedures (TTPs)

Tactic - Technique

TA0001            Initial Access

TA0002            Execution

TA0008            Lateral Movement

TA0003            Persistence

TA0005            Defense Evasion

TA0006            Credential Access

T1021.002       SMB/Windows Admin Shares

T1021  Remote Services

T1566.001       Spearfishing Attachment

T1566  Phishing

T1204.002       Malicious File

T1204  User Execution

T1021.002       SMB/Windows Admin Shares

T1574  Hijack Execution Flow

T1021  Remote Services

T1555.004       Windows Credential Manager

T1555  Credentials from Password Stores

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About the author
Charlotte Thompson
Cyber Analyst
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