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CVE-2021-41091 is an insufficiently restrictive filesystem-permissions vulnerability in Moby (Docker Engine). Subdirectories in the Docker data directory were traversable by otherwise unprivileged local Linux users. This could expose container filesystem contents to host users and permit execution of container-resident programs carrying extended privilege bits. File access could also cross the host/container boundary when a host user's UID or GID matched ownership metadata assigned to files in a container.
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2 valid exploits after Mallory filtered fakes, detection scripts, and README-only repos.
This repository provides an operational exploit for CVE-2021-41091, a privilege escalation vulnerability in Docker Engine (Moby) on Linux systems prior to version 20.10.9. The exploit leverages overly permissive permissions on the overlay2 filesystem, allowing an unprivileged user to access and execute setuid binaries from within a Docker container on the host. The repository contains two main code files: 'exp.sh', a Bash script that checks for a vulnerable Docker version, locates overlay2 filesystems, and attempts to spawn a root shell using a setuid /bin/bash; and 'setuid.c', a small C program that sets UID and GID to 0 and executes /bin/bash as root. The README provides detailed exploitation steps, including setting the setuid bit on /bin/bash inside a container and then running the exploit script on the host. The main fingerprintable endpoints are the '/var/lib/docker/overlay2' directory and '/bin/bash'. The exploit is not part of a framework and is intended for local privilege escalation on vulnerable Docker hosts.
This repository provides an operational exploit for CVE-2021-41091, a privilege escalation vulnerability in Docker Engine (Moby) on Linux systems with versions lower than 20.10.9. The exploit consists of a Bash script ('exp.sh') and a detailed README. The attack requires the user to have unprivileged access on the host and root access inside a Docker container. The attacker sets the setuid bit on /bin/bash inside the container, then uses the script on the host to search for accessible overlay2 filesystems. If the vulnerable conditions are met, the script attempts to spawn a root shell by executing the setuid bash binary exposed via the overlay2 mount. The main fingerprintable endpoints are the Docker overlay2 directory ('/var/lib/docker/overlay2') and the setuid bash binary ('/bin/bash'). The exploit is operational, requiring some manual steps but providing a working privilege escalation path if the system is vulnerable.
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