Cyber Security Threat Summary:
“During the DFIR investigation conducted in May 2023, a significant intrusion was observed, involving the deployment of Truebot, Cobalt Strike, FlawedGrace (also known as GraceWire & BARBWIRE), and the subsequent deployment of the MBR Killer wiper. The threat actors executed their attack swiftly, successfully exfiltrating data and rendering numerous systems inoperable with the wiper within a span of 29 hours after gaining initial access.

After execution, Truebot replicated itself and adopted a new name. It then proceeded to load FlawedGrace onto the compromised host, making various modifications to the system's registry and Print Spooler service. These alterations granted the malware escalated privileges and established persistence. FlawedGrace employed a sophisticated execution routine, involving the storage and extraction of encoded and encrypted payloads in the registry, creation of temporary scheduled tasks, and injection of the final payload into msiexec.exe and svchost.exe.

Approximately five hours after the initial access, the threat actors abruptly ceased their activities, resulting in a period of dormancy for FlawedGrace and Cobalt Strike on all hosts, except the beachhead system. However, after a dormant period of seventeen hours, the threat actors resurfaced within the network, issuing enumeration commands to identify network shares. During this time, DFIR experts detected ongoing signs of data exfiltration from the compromised environment.

Within 29 hours of gaining initial access, the threat actors unleashed the MBR Killer wiper on all compromised hosts, including a file server. The wiper overwrote the Master Boot Record (MBR) of the affected systems, triggering a reboot and rendering them unusable. As a result, numerous systems were left at the boot screen, effectively incapacitated. The threat actors successfully executed their destructive plan, leaving the network compromised and data exfiltrated” (thedfirreport.com, 2023).

Security Officer Comments:
The threat actors utilized email to gain access to the network, sending phishing emails with a deceptive link that led to a malicious file download. The victims were redirected through multiple URLs until they reached a final landing page where they downloaded a file disguised as an Adobe Acrobat document, but it was actually a Truebot executable. Once executed, Truebot replicated itself and assumed a new name, establishing control over the compromised host. The intrusion involved several threat actors, including the Silence group associated with Truebot and TA505, Lace Tempest who conducted a Cl0p ransomware operation, and FIN11 who deployed TRUECORE and BARBWIRE. The presence of overlapping tactics suggests the involvement of Lace Tempest, FIN11, and potential connections to TA505.

MITRE Attack:

• Initial Access: T1566.002: Spearphishing Link
• Execution: TrueBot - T1053.005: Scheduled Task Impacket/atexec - T1059.001: PowerShell, T1204.002: Malicious File
• Persistence: Flawed Grace - T1053.005: Scheduled Task, T1078.003: Valid Accounts
• Privelage Escalation:
• Truebot, Cobalt Strike, Flawed Grace - T1053.005 Scheduled Task T1543.003 Windows Service Defense Evasion:
• Truebot, Flawed Grace, Cobalt Strike, MBR Killer -T1027.010 - Command Obfuscation, T1027.011- Fileless Storage, T1055 Process Injection, T1036.005 - Match Legitimate Name or Location, T1140 - Deobfuscate/Decode Files or Information, T1562.001 - Disable or Modify Tools
• Credential Access:
• Cobalt Strike - T1003.001 LSAAS Memory
• Impacket / SecretDump - T1003.002 Security Account Manager
• Discovery:
• Combination of Native OS commands and Powershell -T1087.002 - Domain Account, T1069.002 Domain Groups, T1492 Domain Trust Discovery, T1083 File and Directory Discovery, T1069.001 Local Groups, T1057 - Process Discovery, T1012 - Query Registry, T1018 Remote System Discovery, T1518.001 Security Software Discovery, T1033 System Owner/User Discovery
• Lateral Movement:
• Cobalt Strike, Flawed Grace - T1021.002 - SMB/Windows Admin Shares, T1550.002, Use Alternate Authentication Material: Pass the Hash
• Collection:
• T1074.001 Local Data Staging
• Command and Control:
• Truebot, FlawedGrace, Cobalt Strike - T107.001 - Web Protocols, T1094 - Custom Command and Control Protocol
• Exfiltration:
• T1048 - Exfiltration Over Alternate Protocol
• Impact:
• MBR Killer - T1561-002 - Disk Structure Wipe
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Suggested Correction(s):
Users should always be cautious of individuals or organizations that ask for personal information. Most companies will not ask for sensitive data from its customers. If in doubt, users should verify with the company itself to avoid any potential issues.

Users should always take a close look at the sender’s display name when checking the legitimacy of an email. Most companies use a single domain for their URLs and emails, so a message that originates from a different domain is a red flag.

As a general rule, users should not click links or download files even if they come from seemingly “trustworthy” sources.

Check for mismatched URLs. While an embedded URL might seem perfectly valid, hovering above it might show a different web address. In fact, users should avoid clicking links in emails unless they are certain that it is a legitimate link.

Users should always be on the lookout for any grammatical errors and spelling mistakes. Legitimate companies will often employ proofreaders and editors who ensure that the materials they send out are error-free.

Users should not be frightened or intimidated by messages that have an alarmist tone. They should double check with the company if they are uncertain about the status of their accounts.

Phishing emails are designed to be sent to a large number of people, so they need to be as impersonal as possible. Users should check whether the message contains a generic subject and greeting, as this can be a sign of a phishing attempt.

Although not every end user has access to advanced anti-phishing software, they can still use the built-in protection of their email clients to filter messages. One example is setting the email client to block all images unless approved.

Legitimate companies will never send confirmation emails unless there are specific reasons for doing so. In fact, most companies will avoid sending unsolicited messages unless it’s for company updates, newsletters, or advertising purposes.

Users should always take the context of an email or message into account. For example, most online accounts do away with viewable member numbers, so users should be wary if they receive emails containing a “member number” for services that generally don’t use them.

It is important to take note of unusual information in the text of the message. Any mentions of operating systems and software that are not typically used by consumers can often be indicators of a phishing attempt.

If it seems suspicious, it probably is. Users should always err on the side of caution when it comes to sending out personally identifiable information through messages and emails.

Link(s):
https://thedfirreport.com/2023/06/12/a-truly-graceful-wipe-out/
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