Privilege Escalation in Sudo via Non-Fatal Privilege Drop Failure

Executive Summary

This vulnerability exists in the sudo program versions through 1.9.17p2 before a specific patch (commit 3e474c2). It occurs because when sudo tries to drop privileges before running its mailer process, failures in system calls that set user ID (setuid), group ID (setgid), or supplementary groups (setgroups) are not treated as fatal errors. This means that if these calls fail, the mailer may still run with elevated privileges, potentially allowing an attacker to escalate their privileges on the system.

The patch fixes this by ensuring that both user and group IDs are properly set and that any failure in these calls causes the process to exit immediately, preventing the mailer from running with incorrect privileges.

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Impact Analysis

This vulnerability can lead to privilege escalation, where an unprivileged user might gain higher privileges than intended. Specifically, because the mailer process may run with incorrect or elevated privileges if the privilege dropping calls fail silently, an attacker could exploit this to execute code with elevated rights, compromising system security.

Such privilege escalation can allow unauthorized access to sensitive data, modification of system files, or execution of arbitrary commands with elevated privileges.

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Detection Guidance

There is no specific information provided about detection methods or commands to identify this vulnerability on a network or system.

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Mitigation Strategies

To mitigate this vulnerability, update the sudo package to a version that includes the fix from commit 3e474c2 or later.

The fix ensures that failures in setuid(), setgid(), or setgroups() calls during the mailer execution are treated as fatal errors, preventing privilege escalation.

Ensure your sudo version is at least 1.9.17p2 with the patch applied or a later secure release.

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Compliance Impact

The provided context and resources do not explicitly discuss the impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.

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