CVE-2019-18684

Description

Sudo through 1.8.29 allows local users to escalate to root if they have write access to file descriptor 3 of the sudo process. This occurs because of a race condition between determining a uid, and the setresuid and openat system calls. The attacker can write "ALL ALL=(ALL) NOPASSWD:ALL" to /proc/#####/fd/3 at a time when Sudo is prompting for a password. NOTE: This has been disputed due to the way Linux /proc works. It has been argued that writing to /proc/#####/fd/3 would only be viable if you had permission to write to /etc/sudoers. Even with write permission to /proc/#####/fd/3, it would not help you write to /etc/sudoers

Weakness classification

• CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Primary references

• cve@mitre.org — Exploit, Third Party Advisory
• af854a3a-2127-422b-91ae-364da2661108 — Exploit, Third Party Advisory