Bug 1771690 (CVE-2019-18684) - CVE-2019-18684 sudo: privilege escalation via write access to file descriptor 3 of the sudo process
Summary: CVE-2019-18684 sudo: privilege escalation via write access to file descriptor...
Keywords:
Status: CLOSED NOTABUG
Alias: CVE-2019-18684
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks: 1771692
TreeView+ depends on / blocked
 
Reported: 2019-11-12 19:18 UTC by msiddiqu
Modified: 2019-11-19 16:09 UTC (History)
8 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed: 2019-11-18 13:26:16 UTC
Embargoed:

Attachments (Terms of Use)

Description msiddiqu 2019-11-12 19:18:46 UTC 
Sudo through 1.8.29 allows local users to escalate to root if they have writeaccess to file descriptor 3 of the sudo process. This occurs because of a racecondition 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 atime when Sudo is prompting for a password.

References: 
 
https://gist.github.com/oxagast/51171aa161074188a11d96cbef884bbd
Comment 1 Riccardo Schirone 2019-11-18 13:26:16 UTC 
Closing this flaw bug as NOTABUG as the CVE has been DISPUTED.

To be able to access /proc/<sudo-pid>/fd/<sudoers-fd>, an attacker should already be able to access it.
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