Sophos Firewall Authentication Bypass Vulnerability

This authentication bypass vulnerability is exploited by remote attackers via the User Portal and Webadmin components. This vulnerability allows an attacker to execute arbitrary code on the victim machine. It was actively exploited by Chinese state-sponsored APT groups, including "Drifting Cloud," to target organizations and governments across South Asia, particularly in Afghanistan, Bhutan, India, Nepal, Pakistan, and Sri Lanka. The attackers leveraged this vulnerability to deploy webshells, conduct man-in-the-middle attacks by modifying DNS responses, and intercept user credentials and session cookies from content management systems. This vulnerability was exploited by Chinese state-sponsored threat actors as part of a broader campaign named "Pacific Rim." This campaign involved multiple Chinese APT groups, including APT31, APT41, and Volt Typhoon, targeting Sophos firewalls. The backdoor PygmyGoat, a novel rootkit that takes the form of a shared object ("libsophos.so"), has been found to be delivered following the exploitation of this vulnerability. The use of the rootkit was observed between March and April 2022 on a government device and a technology partner, and again in May 2022 on a machine in a military hospital based in Asia. This vulnerability was also exploited by at least two advanced persistent threat (APT) groups in a highly targeted attack campaign. The attackers used the vulnerability to place malicious files into a fixed filesystem location on affected devices, leveraging a combination of authentication bypass and command injection to execute arbitrary commands as root. The attack involved deploying various malware families, including GoMet and Gh0st RAT, to maintain persistent access and exfiltrate sensitive data. The attackers demonstrated significant knowledge of the device firmware, using custom ELF binaries and runtime packers like VMProtect to complicate analysis. They manipulated internal commands to move and manipulate files, execute processes, and exfiltrate data. The campaign targeted network security devices, employing a two-stage attack to drop remote access tools and execute commands remotely.