CVE-2022-24769

Moby is an open-source project created by Docker to enable and accelerate software containerization. A bug was found in Moby (Docker Engine) prior to version 20.10.14 where containers were incorrectly started with non-empty inheritable Linux process capabilities, creating an atypical Linux environment and enabling programs with inheritable file capabilities to elevate those capabilities to the permitted set during execve(2). Normally, when executable programs have specified permitted file capabilities, otherwise unprivileged users and processes can execute those programs and gain the specified file capabilities up to the bounding set. Due to this bug, containers which included executable programs with inheritable file capabilities allowed otherwise unprivileged users and processes to additionally gain these inheritable file capabilities up to the containers bounding set. Containers which use Linux users and groups to perform privilege separation inside the container are most directly impacted. This bug did not affect the container security sandbox as the inheritable set never contained more capabilities than were included in the containers bounding set. This bug has been fixed in Moby (Docker Engine) 20.10.14. Running containers should be stopped, deleted, and recreated for the inheritable capabilities to be reset. This fix changes Moby (Docker Engine) behavior such that containers are started with a more typical Linux environment. As a workaround, the entry point of a container can be modified to use a utility like capsh(1) to drop inheritable capabilities prior to the primary process starting.

Weakness

The product specifies permissions for a security-critical resource in a way that allows that resource to be read or modified by unintended actors.

Affected Software

Potential Mitigations

• Run the code in a “jail” or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software.
• OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations.
• This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise.
• Be careful to avoid CWE-243 and other weaknesses related to jails.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/1.html
• https://cwe.mitre.org/data/definitions/122.html
• https://cwe.mitre.org/data/definitions/127.html
• https://cwe.mitre.org/data/definitions/17.html
• https://cwe.mitre.org/data/definitions/180.html
• https://cwe.mitre.org/data/definitions/206.html
• https://cwe.mitre.org/data/definitions/234.html
• https://cwe.mitre.org/data/definitions/60.html
• https://cwe.mitre.org/data/definitions/61.html
• https://cwe.mitre.org/data/definitions/62.html
• https://cwe.mitre.org/data/definitions/642.html

References

• http://www.openwall.com/lists/oss-security/2022/05/12/1
• https://github.com/moby/moby/commit/2bbc786e4c59761d722d2d1518cd0a32829bc07f
• https://github.com/moby/moby/releases/tag/v20.10.14
• https://github.com/moby/moby/security/advisories/GHSA-2mm7-x5h6-5pvq
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6PMQKCAPK2AR3DCYITJYMMNBEGQBGLCC/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/A5AFKOQ5CE3CEIULWW4FLQKHFFU6FSYG/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/A5FQJ3MLFSEKQYCFPFZIKYGBXPZUJFVY/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FPOJUJZXGMIVKRS4QR75F6OIXNQ6LDBL/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HIMAHZ6AUIKN7AX26KHZYBXVECIOVWBH/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HQCVS7WBFSTKJFNX5PGDRARMTOFWV2O7/
• https://security.gentoo.org/glsa/202401-31
• https://www.debian.org/security/2022/dsa-5162