Description
An adversary may abuse configurations where an application has the setuid or setgid bits set in order to get code running in a different (and possibly more privileged) user’s context. On Linux or macOS, when the setuid or setgid bits are set for an application binary, the application will run with the privileges of the owning user or group respectively.(Citation: setuid man page) Normally an application is run in the current user’s context, regardless of which user or group owns the application. However, there are instances where programs need to be executed in an elevated context to function properly, but the user running them may not have the specific required privileges.
Instead of creating an entry in the sudoers file, which must be done by root, any user can specify the setuid or setgid flag to be set for their own applications (i.e. Linux and Mac Permissions). The chmod command can set these bits with bitmasking, chmod 4777 [file] or via shorthand naming, chmod u+s [file]. This will enable the setuid bit. To enable the setgid bit, chmod 2775 and chmod g+s can be used.
Adversaries can use this mechanism on their own malware to make sure they're able to execute in elevated contexts in the future.(Citation: OSX Keydnap malware) This abuse is often part of a "shell escape" or other actions to bypass an execution environment with restricted permissions.
Alternatively, adversaries may choose to find and target vulnerable binaries with the setuid or setgid bits already enabled (i.e. File and Directory Discovery). The setuid and setguid bits are indicated with an "s" instead of an "x" when viewing a file's attributes via ls -l. The find command can also be used to search for such files. For example, find / -perm +4000 2>/dev/null can be used to find files with setuid set and find / -perm +2000 2>/dev/null may be used for setgid. Binaries that have these bits set may then be abused by adversaries.(Citation: GTFOBins Suid)
Platforms
Mitigations (1)
Operating System ConfigurationM1028
Applications with known vulnerabilities or known shell escapes should not have the setuid or setgid bits set to reduce potential damage if an application is compromised. Additionally, the number of programs with setuid or setgid bits set should be minimized across a system.
Associated Software (2)
| ID | Name | Type | Context |
|---|---|---|---|
| S0276 | Keydnap | Malware | [Keydnap](https://attack.mitre.org/software/S0276) adds the setuid flag to a binary so it can easily elevate in the future.(Citation: OSX Keydnap malw... |
| S0401 | Exaramel for Linux | Malware | [Exaramel for Linux](https://attack.mitre.org/software/S0401) can execute commands with high privileges via a specific binary with setuid functionalit... |
References
- Emilio Pinna, Andrea Cardaci. (n.d.). GTFOBins. Retrieved January 28, 2022.
- Marc-Etienne M.Leveille. (2016, July 6). New OSX/Keydnap malware is hungry for credentials. Retrieved July 3, 2017.
- Michael Kerrisk. (2017, September 15). Linux Programmer's Manual. Retrieved September 21, 2018.
Frequently Asked Questions
What is T1548.001 (Setuid and Setgid)?
T1548.001 is a MITRE ATT&CK technique named 'Setuid and Setgid'. It belongs to the Privilege Escalation tactic(s). An adversary may abuse configurations where an application has the setuid or setgid bits set in order to get code running in a different (and possibly more privileged) user’s context. On Linux or macO...
How can T1548.001 be detected?
Detection of T1548.001 (Setuid and Setgid) typically involves monitoring system logs, network traffic, and endpoint telemetry. Use SIEM rules, EDR solutions, and behavioral analytics to identify suspicious activity associated with this technique.
What mitigations exist for T1548.001?
There are 1 documented mitigations for T1548.001. Key mitigations include: Operating System Configuration.
Which threat groups use T1548.001?
While specific threat group attribution may vary, this technique has been observed in various real-world attacks. Check the MITRE ATT&CK website for the latest threat intelligence.