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 File and Directory Permissions Modification). The <code>chmod</code> command can set these bits with bitmasking, <code>chmod 4777 [file]</code> or via shorthand naming, <code>chmod u+s [file]</code>. This will enable the setuid bit. To enable the setgid bit, <code>chmod 2775</code> and <code>chmod g+s</code> 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 <code>ls -l</code>. The <code>find</code> command can also be used to search for such files. For example, <code>find / -perm +4000 2>/dev/null</code> can be used to find files with setuid set and <code>find / -perm +2000 2>/dev/null</code> may be used for setgid. Binaries that have these bits set may then be abused by adversaries.(Citation: GTFOBins Suid)
View in MITRE ATT&CK®| Capability ID | Capability Description | Mapping Type | ATT&CK ID | ATT&CK Name | Notes |
|---|---|---|---|---|---|
| PR.PS-01.01 | Configuration baselines | Mitigates | T1548.001 | Setuid and Setgid |
Comments
This diagnostic statement provides for securely configuring production systems. This includes hardening default configurations and making security-focused setting adjustments to reduce the attack surface, enforce best practices, and protect sensitive data thereby mitigating adversary exploitation.
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| PR.PS-01.02 | Least functionality | Mitigates | T1548.001 | Setuid and Setgid |
Comments
This diagnostic statement provides for limiting unnecessary software, services, ports, protocols, etc. Ensuring systems only have installed and enabled what is essential for their operation reduces the attack surface and minimizes vulnerabilities, which mitigates a wide range of techniques.
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| PR.PS-01.03 | Configuration deviation | Mitigates | T1548.001 | Setuid and Setgid |
Comments
This diagnostic statement provides protection from Abuse Elevation Control Mechanism: Setuid and Setgid through the implementation of security configuration baselines for OS, software, file integrity monitoring and imaging. Security baseline configuration of the Operating System and integrity checking can help protect against adversaries attempting to compromise and elevate privileges.
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| Capability ID | Capability Description | Mapping Type | ATT&CK ID | ATT&CK Name | Notes |
|---|---|---|---|---|---|
| CM-06 | Configuration Settings | mitigates | T1548.001 | Setuid and Setgid | |
| CM-07 | Least Functionality | mitigates | T1548.001 | Setuid and Setgid | |
| SI-04 | System Monitoring | mitigates | T1548.001 | Setuid and Setgid |
| Capability ID | Capability Description | Mapping Type | ATT&CK ID | ATT&CK Name | Notes |
|---|---|---|---|---|---|
| action.hacking.variety.Abuse of functionality | Abuse of functionality. | related-to | T1548.001 | Setuid and Setgid |
| Capability ID | Capability Description | Mapping Type | ATT&CK ID | ATT&CK Name | Notes |
|---|---|---|---|---|---|
| docker_host_hardening | Microsoft Defender for Cloud: Docker Host Hardening | technique_scores | T1548.001 | Setuid and Setgid |
Comments
This control may provide recommendations to remove setuid and setguid permissions from container images. It may not be feasible to audit and remediate all binaries that have and require setuid and setguid permissions.
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