ConnectWise, a prominent software company, issued an urgent security bulletin on February 19, 2024, revealing two significant vulnerabilities in its self-hosted ScreenConnect servers.
These vulnerabilities were initially reported on February 13 through a vulnerability disclosure program and were not actively exploited until February 20.
The first vulnerability, identified as CVE-2024-1708, is a path traversal issue with a high severity score of 8.4.
The second, CVE-2024-1709, is a remote code execution flaw with a maximum severity score of 10.0, indicating a critical risk.
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Analysis by the Shadowserver Foundation, & Shodan search engine found over 8,200 publicly accessible, unpatched ScreenConnect servers, predominantly in the United States, Canada, and the United Kingdom.
Exploits and Malware Distribution
By February 21, a proof-of-concept exploit was uploaded to GitHub, and a Metasploit module for CVE-2024-1709 was released, making the vulnerabilities easily exploitable by hackers of varying skill levels.
Secureworks researchers discovered that several of their customers’ servers had been scanned for these vulnerabilities, with some showing evidence of intrusion.
One incident involved the execution of a Cobalt Strike Beacon payload through a compromised ScreenConnect server.
Another attack involved downloading a legitimate SentinelUI.exe file, a DLL, and an encrypted file containing an encoded payload.
This malware impersonated Microsoft Windows Update network traffic for communication.
Huntress and Sophos reported similar incidents where Cobalt Strike Beacon and other malware like LockBit ransomware and AsyncRAT were distributed after exploiting these vulnerabilities.
Organizations are recommended to immediately upgrade vulnerable ScreenConnect servers and conduct forensic examinations for signs of exploitation.
They also recommend using available controls to review and restrict access based on the indicators provided in their security bulletin.
Secureworks Counter Threat shared a list of IP addresses and domain names associated with the attacker infrastructure, MD5, SHA1, and SHA256 hashes of the distributed Cobalt Strike Beacon DLLs and other malware samples; the list can be found here.
Organizations should consider the risks before opening these indicators in a browser, as they may contain malicious content.
ConnectWise’s security bulletin serves as a critical alert for organizations using ScreenConnect servers to take immediate action to protect their networks from these serious threats.
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