Ivanti recently disclosed a critical buffer overflow vulnerability (CVE-2025-0282) affecting its Connect Secure VPN appliances. This flaw is caused by improper handling of the strncpy function in the web server component, enabling attackers to execute arbitrary code remotely. Exploitation of this vulnerability was first confirmed in Japan in December 2024, even before Ivanti’s official advisory. Researchers found that the malware exploiting this flaw, a new variant of the SPAWN malware family, named “SPAWNCHIMERA,” was not only capable of exploiting the flaw but also deploying a self-contained fix to prevent other attackers from using the same vulnerability.
SPAWNCHIMERA is an evolution of previous SPAWN malware variants (SPAWNANT, SPAWNMOLE, SPAWNSNAIL), combining their functionalities into a more advanced modular framework. Its primary objectives include maintaining persistent access to compromised systems, enabling lateral movement, and intercepting network traffic through injected processes.
Researchers noted several improvements in SPAWNCHIMERA, such as refined UNIX domain socket communication.
Enhanced XOR-based decoding routines for stealth, and stripped debug messages, making it more difficult to detect and analyze.
What makes SPAWNCHIMERA particularly unique is its built-in vulnerability patch that neutralizes the buffer overflow flaw it exploits. The malware hijacks the strncpy function and modifies it to limit buffer copies to 256 bytes, effectively preventing the overflow. This mechanism works by checking if the running process name corresponds to the vulnerable service, then automatically truncating any buffer operations that exceed the size limit. However, if the malware identifies a specific bypass signature in the source buffer, it allows for selective exploitation while still keeping the attack hidden from security tools.
This unorthodox approach—exploiting a vulnerability while simultaneously patching it—poses a significant challenge for cybersecurity teams. It prevents other threat actors from exploiting the same vulnerability, destabilizing competing campaigns. At the same time, security teams analyzing compromised systems may mistakenly believe that the vulnerability has already been patched, potentially overlooking the malware’s persistence mechanisms. Cybersecurity experts are advising immediate patching of Ivanti appliances and vigilance for suspicious artifacts, such as certain UNIX sockets and shared objects, in order to prevent further compromise.
