Bind Mounts

What the technique is

Adversaries may abuse bind mounts on file structures to hide their activity and artifacts from native utilities. A bind mount maps a directory or file from one location on the filesystem to another, similar to a shortcut on Windows. It’s commonly used to provide access to specific files or directories across different environments, such as inside containers or chroot environments, and requires sudo access. Adversaries may use bind mounts to map either an empty directory or a benign /proc directory to a malicious process’s /proc directory. Using the commands mount –o bind /proc/benign-process /proc/malicious-process (or mount –B), the malicious process's /proc directory is overlayed with the contents of a benign process's /proc directory. When system utilities query process activity, such as ps and top, the kernel follows the bind mount and presents the benign directory’s contents instead of the malicious process's actual /proc directory. As a result, these utilities display information that appears to come from the benign process, effectively hiding the malicious process's metadata, executable, or other artifacts from detection.

What MITRE says you would watch

• AN1196

  Abuse of bind mounts to obscure process directories. Defender perspective: detecting anomalous mount operations where a process’s /proc entry is remapped to another directory, often hiding malicious activity from native utilities (ps, top). Behavior chain includes: (1) execution of mount with -o bind or -B flags, (2) modification of /proc entries inconsistent with expected process lineage, and (3) subsequent anomalous activity from processes whose metadata no longer matches execution context.