Abuse of Mavinject for Process Injection

Mavinject (mavinject.exe) is a signed Microsoft Windows utility originally designed for the Application Virtualization (App-V) environment. The tool provides a capability to inject a DLL into a running process using the /INJECTRUNNING flag. Because mavinject.exe is a trusted, signed binary, threat actors often use it as a Living-off-the-Land (LotL) technique to perform process injection while evading security controls that monitor for unsigned or suspicious executables. This technique allows an attacker to execute malicious code within the memory space of a legitimate, already-running process, potentially leading to privilege escalation or persistence. Defenders should monitor for execution of this binary where the parent process is not the legitimate App-V client.

Impact

The abuse of this utility facilitates stealthy execution of malicious payloads, allowing attackers to hide their activity within the memory space of legitimate system or application processes. This can lead to unauthorized access to process data, privilege escalation, and evasion of endpoint detection mechanisms that rely on process reputation.

Recommendation

Deploy the provided Sigma rule to monitor for suspicious invocations of mavinject.exe. Ensure that all command-line arguments are captured in process creation logs (Event ID 1). If mavinject.exe is not utilized by authorized App-V configurations in your environment, consider monitoring all instances of this binary regardless of the parent process.