Conti Ransomware Group Finds New Double Extortion Avenues
07
Dec 2021
Discover how Darktrace was able to detect one of Conti Ransomware Groups crippling double extortion attacks at its earliest stages. Learn more now!
In a previous blog, we outlined how the Ryuk ransomware strain developed by Russian hacking group ‘Wizard Spider’ has fallen into the hands of small-time cyber criminals.
Wizard Spider – who allegedly operate with support from the Russian government and remain under investigation by the FBI and Interpol – adopted Ryuk ransomware’s successor ‘Conti’ in 2020. Conti affects all Windows operating systems and has been involved in more than 400 incidents. Wizard Spider were soon rebranded in cyber press as the ‘Conti Ransomware Gang’, though the group does not necessarily see itself as a ‘gang’. It prefers to present itself as a business.
The ransomware bubble
Ransomware has become a multibillion-dollar industry – and the Conti Ransomware Gang reportedly made up 15% of it in 2020. With this scale of income, groups like Conti find themselves adopting some crude imitations of legitimate business practice. This corporate mimicry dictates that their victims be called ‘customers’, their extortion attempts ‘negotiations’ and their criminal peers ‘affiliates’. They even publish ‘press releases’ via a dedicated Dark Web site.
The gang’s Ransomware-as-a-Service ‘business model’ consists of employing affiliates, training them in Conti ransomware’s deployment and management, and then taking 30% of the profits themselves. With exact profits known only to the malware writers and not the affiliates, however, the percentage Conti takes is often much higher than the 30% they claim.
There may not be checks and regulations in place to address fraud in the cyber underworld, but one business complication which Conti have not been able to escape is that of the disgruntled employee.
Unhappy with the malpractice of their superiors, an underpaid affiliate leaked the Conti Ransomware Gang’s training materials and the IP addresses for their Cobalt Strike C2 servers in August 2021, declaring, “they recruit suckers and divide the money among themselves”.
Meanwhile, the US Government has also been taking action to try to disrupt the profit margins of groups like the Conti Ransomware Gang, going as far as to impose sanctions on cryptocurrency exchanges seen as facilitating ransomware transactions. However, leaks and legislation have proved far from fatal for Conti.
The reality is that these actions have not lost the Conti Ransomware Gang any of its so-called “customers”, and where there are customers there is profit. Any individual or organization entrusting their cyber security to conventional, rules-based measures is in their target market.
Darktrace’s AI recently detected a Conti attack conducted along the lines of one of the methods outlined in the August leak. The target organization – a US transportation company – was trialing Darktrace but, without Darktrace’s Autonomous Response set in active mode, the attack was allowed to go ahead. In examining how it progressed, however, it should become clear not only how threatening double extortion ransomware attacks like this one can be, but also how effectively they can be stopped by Darktrace at each stage of the attack.
Figure 1: Timeline of the attack
Conti Ransomware Gang diversifies the ransomware playbook
A single uninstalled Microsoft patch had left the target organization with dangerous ProxyShell vulnerabilities. Conti exploited these vulnerabilities, quickly gaining the rights to remotely execute Exchange PowerShell commands on the company’s server and steadily broadened its presence within the digital environment. This is a relatively new approach for the Conti Ransomware Gang, who previously relied upon phishing attacks and firewall exploits. By diversifying its approach, it stays ahead of patches and intelligence.
Two weeks after the initial breach, C2 connections were made to an unusual endpoint located in Finland using an SSL client which appeared innocuous but was 100% rare for the organization. Had Autonomous Response been set in active mode, Darktrace would have shut the connections down at this very early stage.
The IP address of this suspicious endpoint has since been identified as a Conti IoC (Indicator of Compromise), allowing it to be incorporated into rules-based security solutions. This would have done little good for the company in question, however, which was breached weeks before this intelligence was made available.
As Conti continued to conduct internal reconnaissance and move laterally through the company’s digital environment, Darktrace detected further unusual activity. The suspicious Finnish endpoint then employed new ‘Living off the Land’ techniques, installing the usually legitimate tools AnyDesk and Cobalt Strike onto various parts of the environment.
A series of SSL connections were made to AnyDesk endpoints and external hosts, one of which lasted 95 hours, indicating an active remote session conducted by one of Conti’s affiliates. At this stage, Darktrace had 10 distinct reasons to suspect an imminent attack.
Conti News: Closing the deal with double extortion ransomware
Double extortion has become the Conti Ransomware Gang’s new favourite sales tactic. If you refuse to pay its ransom, Conti will not only take your most important files from you, but also exfiltrate and publish them using its dedicated ‘Conti News’ website, or sell them directly to your competitors.
Having expanded their reach across the transport company’s network, the Conti affiliate began rapidly exfiltrating large quantities of company data to Conti’s preferred cloud storage site, MEGA. Over four days, more than 3TB of data was uploaded, and then encrypted.
To avoid detection by a human security team, encryption was launched at close to midnight – Conti’s ‘business’ does not respect business hours. When the company’s security team returned to work the next day, they were met with a ransom note.
This attack was able to progress because Darktrace was only being trialed at this stage and was therefore allowed to detect threats but not to take action against them. With Autonomous Response employed in active mode, this ransomware attack would have ended in the very early stages, when Darktrace detected its first suspicious connections.
Nonetheless, the Cyber AI Analyst was able to investigate and connect the dots of the attack automatically, making the organization’s remediation efforts drastically quicker and easier than they would have been without even this partial Darktrace deployment.
Figure 2: Cyber AI Analyst generated this incident report following the initiation of data exfiltration
How the Conti Ransomware Gang evades cyber intelligence
Security systems that rely on human intelligence to detect threats fit Conti’s ideal customer profile perfectly. By adapting and diversifying their approach, moving from Ryuk to Conti, and from spear phishing and firewall exploits to this new ProxyShell approach, Conti stay ahead of regulations and hold on to their vulnerable customer base.
Even if the Conti Ransomware Gang is brought down by leaks or legislation, other groups will rise to fill the gap in the market, eager for their own cut of the illicit gains. If these groups are to be truly stopped, they must be made unprofitable.
The US government has tried to do this by imposing fines upon ransom payers, but companies still often consider the losses involved in not recovering their data too great. As I have argued previously, ‘to pay or not to pay,’ is not the question we should be asking.
If you’re deciding whether to pay or not to pay, you’re already too far down the line. Darktrace stops groups like Conti at the first encounter. As this case has shown, Darktrace’s Self-Learning AI is able to identify threats weeks before human analysts and threat intelligence can do the same, and neutralize them at every stage of an attack with Autonomous Response.
Thanks to Darktrace analyst Sam Lister for his insights on the above threat find.
Darktrace model detections:
Device / Long Agent Connection to New Endpoint
Device / ICMP Address Scan
Anomalous Connection / SMB Enumeration
Anomalous Server Activity / Outgoing from Server
Compromise / Beacon to Young Endpoint
Anomalous Server Activity / Rare External from Server
Compromise / Fast Beaconing to DGA
Compromise / SSL or HTTP Beacon
Compromise / Sustained SSL or HTTP Increase
Compromise / Beacon for 4 Days
Anomalous Connection / Multiple HTTP POSTs to Rare Hostname
Unusual Activity / Enhanced Unusual External Data Transfer
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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
Justin Fier
SVP, Red Team Operations
Justin is one of the US’s leading cyber intelligence experts, and holds the position of SVP, Red Team Operations at Darktrace. His insights on cyber security and artificial intelligence have been widely reported in leading media outlets, including the Wall Street Journal, CNN, The Washington Post, and VICELAND. With over 10 years’ experience in cyber defense, Justin has supported various elements in the US intelligence community, holding mission-critical security roles with Lockheed Martin, Northrop Grumman Mission Systems and Abraxas. Justin is also a highly-skilled technical specialist, and works with Darktrace’s strategic global customers on threat analysis, defensive cyber operations, protecting IoT, and machine learning.
From Royal to BlackSuit: Understanding the Tactics and Impact of a Sophisticated Ransomware Strain
What is BlackSuit Ransomware?
Since late 2023, Darktrace has detected BlackSuit ransomware infiltrating multiple customer networks in the US. This ransomware has targeted a wide range of industries, including arts, entertainment, real estate, public administration, defense, and social security.
Emerging in May 2023, BlackSuit is believed to be a spinoff of Royal ransomware due to similarities in code and Conti, and most likely consists of Russian and Eastern European hackers [1]. Recorded Future reported that the ransomware had affected 95 organizations worldwide, though the actual number is likely much higher [2]. While BlackSuit does not appear to focus on any particular sector, it has targeted multiple organizations in the healthcare, eduction, IT, government, retail and manufacturing industries [3]. Employing double extortion tactics, BlackSuit not only encrypts files but also steals sensitive data to leverage ransom payments.
BlackSuit has demanded over USD 500 million in ransoms, with the highest individual demand reaching USD 60 million [4]. Notable targets include CDK Global, Japanese media conglomerate Kadokawa, multiple educational institutions, Octapharma Plasma, and the government of Brazil [5][6][7][8].
Darktrace’s Coverage of BlackSuit Ransomware Attack
Case 1, November 2023
The earliest attack on a Darktrace customer by BlackSuit was detected at the start of November 2023. The unusual network activity began on a weekend—a time commonly chosen by ransomware groups to increase their chances of success, as many security teams operate with reduced staff. Darktrace identified indicators of the attackers’ presence on the network for almost two weeks, during which a total of 15 devices exhibited suspicious behavior.
The attack commenced with unusual internal SMB (Server Message Block) connections using a compromised service account. An internal device uploaded an executable (zzza.exe) to a domain controller (DC) and shortly after, wrote a script (socks5.ps1) to another device. According to a Cybersecurity Advisory from the CISA (Cybersecurity and Infrastructure Security Agency, US), the script file was a PowerShell reverse proxy [9].
Approximately an hour and a half later, the device to which the script was written exhibited uncommon WMI (Windows Management Instrumentation) activity. Two hours after receiving the executable file, the DC was observed making an outgoing NTLM request, using PowerShell to remotely execute commands, distributing differently named executable files (<PART OF THE CUSTOMER’S NAME>.exe), and controlling services on other devices.
Eighteen hours after the start of the unusual activity, Darktrace detected another device making repeated connections to “mystuff.bublup[.]com”, which the aforementioned CISA Advisory identifies as a domain used by BlackSuit for data exfiltration [9].
About ten minutes after the suspicious executables were distributed across the network, and less than 24 hours after the start of the unusual activity, file encryption began. A total of ten devices were seen appending the “.blacksuit” extension to files saved on other devices using SMB, as well as writing ransom notes (readme.blacksuit.txt). The file encryption lasted less than 20 minutes.
Figure 1: An example of the contents of a BlackSuit ransom note being written over SMB.
During this compromise, external connections to endpoints related to ConnectWise’s ScreenConnect remote management tool were also seen from multiple servers, suggesting that the tool was likely being abused for command-and-control (C2) activity. Darktrace identified anomalous connectivity associated with ScreenConnect was seen up to 11 days after the start of the attack.
10 days after the start of the compromise, an account belonging to a manager was detected adding “.blacksuit” extensions to the customer’s Software-a-Service (SaaS) resources while connecting from 173.251.109[.]106. Six minutes after file encryption began, Darktrace flagged the unusual activity and recommended a block. However, since Autonomous Response mode was not enabled, the customer’s security team needed to manually confirm the action. Consequently, suspicious activity continued for about a week after the initial encryption. This included disabling authentication on the account and an unusual Teams session initiated from the suspicious external endpoint 216.151.180[.]147.
Case 2, February 2024
Another BlackSuit compromise occurred at the start of February 2024, when Darktrace identified approximately 50 devices exhibiting ransomware-related activity in another US customer’s environment. Further investigation revealed that a significant number of additional devices had also been compromised. These devices were outside Darktrace’s purview to the customer’s specific deployment configuration. The threat actors managed to exfiltrate around 4 TB of data.
Initial access to the network was gained via a virtual private network (VPN) compromise in January 2024, when suspicious connections from a Romanian IP address were detected. According to CISA, the BlackSuit group often utilizes the services of initial access brokers (IAB)—actors who specialize in infiltrating networks, such as through VPNs, and then selling that unauthorized access to other threat actors [9]. Other initial access vectors include phishing emails, RDP (Remote Desktop Protocol) compromise, and exploitation of vulnerable public-facing applications.
Similar to the first case, the file encryption began at the end of the working week. During this phase of the attack, affected devices were observed encrypting files on other internal devices using two compromised administrator accounts. The encryption activity lasted for approximately six and a half hours. Multiple alerts were sent to the customer from Darktrace’s Security Operations Centre (SOC) team, who began reviewing the activity within four minutes of the start of the file encryption.
Figure 2: Darktrace’s Cyber AI Analyst clustering together multiple events related to unusual activity on the network, including file encryption over SMB by BlackSuit.
Figure 3: A spike in model alerts on the day when file encryption by BlackSuit was observed in the network.
In this case, the threat actor utilized SystemBC proxy malware for command and control (C2). A domain controller (DC) was seen connecting to 137.220.61[.]94 on the same day the file encryption took place. The DC was also observed connecting to a ProxyScrape domain around the same time, which is related to the SOCKS5 protocol used by SystemBC. During this compromise, RDP, SSH, and SMB were used for lateral movement within the network.
Figure 4: A Cyber AI Analyst investigation alerting to a device on the VPN subnet making suspicious internal SSH connections due to malicious actors moving laterally within the network.
Signs of threat actors potentially being on the network were observed as early as two days prior to the file encryption. This included unusual internal network scanning via multiple protocols (ICMP, SMB, RDP, etc.), credential brute-forcing, SMB access failures, and anonymous SMBv1 sessions. These activities were traced to IP addresses belonging to two desktop devices in the VPN subnet associated with two regular employee user accounts. Threat actors were seemingly able to exploit at least one of these accounts due to LDAP legacy policies being in place on the customer’s environment.
Figure 5: A Cyber AI Analyst incident summary alerting to a device on the VPN subnet conducting internal reconnaissance.
Figure 6: Examples of the proposed Darktrace Autonomous Response actions on the day BlackSuit initiated file encryption.
Case 3, August 2024
The most recently observed BlackSuit compromise occurred in August 2024, when a device was observed attempting to brute-force the credentials of an IT administrator. This activity continued for 11 days.
Once the admin’s account was successfully compromised, network scanning, unusual WMI, and SAMR (Security Account Manager Remote protocol) activity followed. A spike in the use of this account was detected on a Sunday—once again, the attackers seemingly targeting the weekend—when the account was used by nearly 50 different devices.
The compromised admin’s account was exploited for data gathering via SMB, resulting in the movement of 200 GB of data between internal devices in preparation for exfiltration. The files were then archived using the naming convention “*.part<number>.rar”.
Around the same time, Darktrace observed data transfers from 19 internal devices to “bublup-media-production.s3.amazonaws[.]com,” totaling just over 200 GB—the same volume of data gathered internally. Connections to other Bublup domains were also detected. The internal data download and external data transfer activity took approximately 8-9 hours.
Unfortunately, Darktrace was not configured in Autonomous Response mode at the time of the attack, meaning any mitigative actions to stop the data gathering or exfiltration required human confirmation.
Figure 7: One of the compromised devices was seen sending 80 GB of data to bublup-media-production.s3.amazonaws[.]com within a span of 4 hours.
Once the information was stolen, the threat actor moved on to the final stage of the attack—file encryption. Five internal devices, using either the compromised admin account or connecting via anonymous SMBv1 sessions, were seen encrypting files and writing ransom notes to five other devices on the network. The attempts at file encryption continued for around two hours, but Darktrace’s Autonomous Response capability was able to block the activity and prevent the attack from escalating.
Conclusion
The persistent and evolving threat posed by ransomware like BlackSuit underscores the critical importance of robust cybersecurity measures across all sectors. Since its emergence in 2023, BlackSuit has demonstrated a sophisticated approach to infiltrating networks, leveraging double extortion tactics, and demanding substantial ransoms. The cases highlighted above illustrate the varied methods and persistence of BlackSuit attackers, from exploiting VPN vulnerabilities to abusing remote management tools and targeting off-hours to maximize impact.
Although many similar connection patterns, such as the abuse of Bublup services for data exfiltration or the use of SOCKS5 proxies for C2, were observed during cases investigated by Darktrace, BlackSuit actors are highly sophisticated and tailors their attacks to each target organization. The consequences of a successful attack can be highly disruptive, and remediation efforts can be time-consuming and costly. This includes taking the entire network offline while responding to the incident, restoring encrypted files from backups (if available), dealing with damage to the organization’s reputation, and potential lawsuits.
These BlackSuit ransomware incidents emphasize the need for continuous vigilance, timely updates to security protocols, and the adoption of autonomous response technologies to swiftly counteract such attacks. As ransomware tactics continue to evolve, organizations must remain agile and informed to protect their critical assets and data. By learning from these incidents and enhancing their cybersecurity frameworks, organizations can better defend against the relentless threat of ransomware and ensure the resilience of their operations in an increasingly digital world.
Credit to Signe Zaharka (Principal Cyber Analyst) and Adam Potter (Senior Cyber Analyst)
Darktrace’s First 6: Half-Year Threat Report 2024 highlights the latest attack trends and key threats observed by the Darktrace Threat Research team in the first six months of 2024.
Focuses on anomaly detection and behavioral analysis to identify threats
Maps mitigated cases to known, publicly attributed threats for deeper context
Offers guidance on improving security posture to defend against persistent threats
Appendices
Darktrace Model Detections
Anomalous Connection / Data Sent to Rare Domain
Anomalous Connection / High Volume of New or Uncommon Service Control
Anomalous Connection / New or Uncommon Service Control
Anomalous Connection / Rare WinRM Outgoing
Anomalous Connection / SMB Enumeration
Anomalous Connection / Suspicious Activity On High Risk Device
Anomalous Connection / Suspicious Read Write Ratio
Anomalous Connection / Suspicious Read Write Ratio and Unusual SMB
Anomalous Connection / Sustained MIME Type Conversion
.blacksuit - File extension – When encrypting the files, this extension is appended to the filename – High
readme.blacksuit.txt – ransom note - A file demanding cryptocurrency payment in exchange for decrypting the victim's files and not leaking the stolen data – High
mystuff.bublup[.]com, bublup-media-production.s3.amazonaws[.]com – data exfiltration domains related to an organization and project management app that has document sharing functionality – High
137.220.61[.]94:4001 – SystemBC C2 related IP address (this tool is often used by other ransomware groups as well) - Medium
173.251.109[.]106 – IP address seen during a SaaS BlackSuit compromise (during file encryption) – Medium
216.151.180[.]147 – IP address seen during a SaaS BlackSuit compromise (during an unusual Teams session) - Medium
MITRE ATT&CK Mapping
Tactic - Technqiue
Account Manipulation - PERSISTENCE - T1098
Alarm Suppression - INHIBIT RESPONSE FUNCTION - T0878
Application Layer Protocol - COMMAND AND CONTROL - T1071
Automated Collection - COLLECTION - T1119
Block Command Message - INHIBIT RESPONSE FUNCTION - T0803
Block Reporting Message - INHIBIT RESPONSE FUNCTION - T0804
Onomastics Gymnastics: How Darktrace Detects Spoofing and Business Email Compromise in Multi-Name Users
Note: For privacy reasons, actual surnames and email addresses observed in these incidents below have been replaced with fictitious placeholder names, using the common Spanish names “Fulano” and “Mengano”.
Naming conventions
Modeling names and their variants of members of an organization is a critical component to properly detect if those same names and variants are being spoofed by malicious actors. For many predominantly English-speaking organizations, these variants can largely be captured by variants of a person’s given name (e.g. James-Jimmy-Jim) and a consistent, singular surname or family name (e.g. Smith). Naming conventions, however, are far from universal. This piece will review how Darktrace / EMAIL manages the common naming conventions of much of the Spanish-speaking world, and can use its modeling to create high-fidelity detections of multiple types of spoofing attempts.
A brief summary of the common convention across Spain and much of Spanish-speaking America: most people are given one or two given names (e.g. Roberto, Juan, María, Natalia), and their surnames are the first surname of their father, followed by the first surname of their mother. While there are various exceptions to this norm, the below graphic Wikipedia [1][2] highlights the general rule.
Figure 1: Example Spanish naming convention for father “José García Torres” and mother “María Acosta Gómez” for child “Pablo García Acosta”. If shortened to one surname, the convention holds the child would be referred to as “Pablo García” [1].
Detection of improper name usage
Implicit in the above comment that shortening to one surname follows the convention of using the first surname, shortening to the second surname is often a tell-tale sign of someone unfamiliar with the person or their broader culture. This can be a useful corroborating feature in detecting a spoof attempt – analogous to a spelling error.
In the case of a Spanish customer, this misuse of name shortening contributed to the detection of a spoof attempt trying to solicit a response by impersonating an internal user forwarding information about ‘Data Protection’.
Figure 2: The Cyber AI Analyst summary of the Darktrace / EMAIL detections shows the use of the Gmail sender impersonating Isabel Maria Fulano Mengano, but incorrectly uses the second surname Mengano.
While the limited communication history from the sender and the nature of the text content already marks the mail as suspicious, Darktrace / EMAIL notes the personal name used in the email is similar to a high-value user (‘whale’ to use the terminology of spearphishing). The additional context provided by the detection of the attempted spoof prompted more severe actioning of this email, leading to a ‘Hold’ action instead of a less-severe ‘Unspoof’ action via a banner on the email.
Figure 3: The content summary of the sender showing the ‘Personal’ field of the email being ‘Isabel Mengano’, breaking from the standard name-shortening convention. The additional metrics identify features that might be anomalous about the sender.
Malicious email properly using both surnames
Misusing the name-shortening convention is not the only way that Darktrace / EMAIL can detect spoofing attempts. In the case of another Spanish customer, Darktrace observed a whale impersonation being sent to 230 users with solicitation content, but no links or attachments. Although the name was modeled internally in the “Surname, Given-name” format, Darktrace identified the spoofing attempt targeting a high-value user and took action, blocking the series of emails from reaching end-user inboxes to prevent unsuspecting users from responding.
Figure 4: Cyber AI Analyst summary of a suspicious email. The personal field is visible as ‘juan fulano mengano’, which is consistent with the reverse-order modelled user ‘fulano mengano, juan’. The subject line ‘Urgent Request’ sent to 230 users gives an intuitive indicator of the emails potentially being part of a malicious solicitation campaign.
In Summary: A case of onomastics gymnastics
The variety in valid usage of human language can be a barrier to evaluating when a given text is benign or malicious. Despite this, Darktrace / EMAIL is designed to manage this variety, as exemplified by the detections of two spoofing attempts seen against organizations using the distinct Spanish-speaking world’s common naming convention. The scope of this design as seen in this onomastic context, extends to a wide range of detections surrounding emails and their behavioral anomalies.
Credit to Roberto Romeu (Principal Cyber Analyst), Justin Torres (Senior Cyber Analyst) and Natalia Sánchez Rocafort (Senior Analyst Consultant).
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![One of the compromised devices was seen sending 80 GB of data to bublup-media-production.s3.amazonaws[.]com within a span of 4 hours.](https://cdn.prod.website-files.com/626ff4d25aca2edf4325ff97/673513f1135d0e009caf256f_6735136a725738f4afe4de2b_Fig%25207.png)
