Pierluigi Paganini February 27, 2024

New threat actors have started exploiting ConnectWise ScreenConnect vulnerabilities, including the Black Basta and Bl00dy ransomware gangs.

Multiple threat actors have started exploiting the recently disclosed vulnerabilities, tracked as CVE-2024-1709 (CVSS score of 10) and CVE-2024-1708 (CVSS score of 8.4), in the ConnectWise ScreenConnect software.

ConnectWise recently warned of the following two critical vulnerabilities in its ScreenConnect remote desktop access product:

• CVE-2024-1709 – CWE-288 Authentication bypass using an alternate path or channel (CVSS score 10)
• CVE-2024-1708 – CWE-22 Improper limitation of a pathname to a restricted directory (“path traversal”)  (CVSS score 8.4)

Both vulnerabilities were reported on February 13, 2024, through the company vulnerability disclosure channel via the ConnectWise Trust Center. The company is not aware of attacks in the wild exploiting these vulnerabilities, however, due to the higher risk of being targeted by exploits, ConnectWise recommends installing updates as emergency changes within days.  

The issues affect ScreenConnect 23.9.7 and prior, below is the remediation provided in the advisory:

Two days after the vendor addressed the two vulnerabilities, it also updated its advisory to confirm the ongoing exploitation of both issues.

Trend Micro researchers observed multiple threat actor groups that are exploiting vulnerabilities in ConnectWise ScreenConnect for different purposes, including ransomware deployment, and data exfiltration attacks.

Trend Micro confirmed that Black Basta and Bl00dy ransomware groups are actively exploiting both flaws and shared details about their attack chains.

Black Basta operators exploit the flaws to gain initial foothold on the vulnerable server, then they perform reconnaissance, discovery, and privilege escalation activities.

The gang was observed deploying the popular post-exploitation tool Cobalt Strike.

The attackers were observed searching for members of the ‘domain admin’ group to identify potential high-value targets for further attacks. Then the attackers also added new accounts to the local administrators group and deployed scripts to identify machines that connected to the Active Directory environment within the past 90 days. The attackers attempt to target these machines in further attacks or use them for lateral movement within the target network.

The Bl00dy ransomware group was also observed exploiting the two flaws in campaigns to deploy leaked builders from Conti and LockBit. The ransom notes deployed in the attacks allowed the researchers to link the attacks to the Bl00dy group.

The researchers also observed attacks where threat actors exploited these vulnerabilities in ScreenConnect via the XWorm malware. XWorm is a versatile malware that not only grants threat actors remote access capabilities, but also allows attackers to propagate through networks, exfiltrate sensitive data, and download additional payloads.

After establishing a presence on the susceptible ConnectWise server, we observed threat actors trying to execute PowerShell commands to download and run the XWORM malware.

Trend Micro also spotted threat actors deploying other remote access software, such as Atera and Syncro.

“Following our detailed examination of various threat actors exploiting vulnerabilities in ConnectWise ScreenConnect, we emphasize the urgency of updating to the latest version of the software.” Trend Micro concludes. “Immediate patching is not just advisable; it is a critical security requirement to protect your systems from these identified threats.”

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Pierluigi Paganini

(SecurityAffairs – hacking, ConnectWise ScreenConnect)