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CVE-2023-42456 Detail

Description

Sudo-rs, a memory safe implementation of sudo and su, allows users to not have to enter authentication at every sudo attempt, but instead only requiring authentication every once in a while in every terminal or process group. Only once a configurable timeout has passed will the user have to re-authenticate themselves. Supporting this functionality is a set of session files (timestamps) for each user, stored in `/var/run/sudo-rs/ts`. These files are named according to the username from which the sudo attempt is made (the origin user). An issue was discovered in versions prior to 0.2.1 where usernames containing the `.` and `/` characters could result in the corruption of specific files on the filesystem. As usernames are generally not limited by the characters they can contain, a username appearing to be a relative path can be constructed. For example we could add a user to the system containing the username `../../../../bin/cp`. When logged in as a user with that name, that user could run `sudo -K` to clear their session record file. The session code then constructs the path to the session file by concatenating the username to the session file storage directory, resulting in a resolved path of `/bin/cp`. The code then clears that file, resulting in the `cp` binary effectively being removed from the system. An attacker needs to be able to login as a user with a constructed username. Given that such a username is unlikely to exist on an existing system, they will also need to be able to create the users with the constructed usernames. The issue is patched in version 0.2.1 of sudo-rs. Sudo-rs now uses the uid for the user instead of their username for determining the filename. Note that an upgrade to this version will result in existing session files being ignored and users will be forced to re-authenticate. It also fully eliminates any possibility of path traversal, given that uids are always integer values. The `sudo -K` and `sudo -k` commands can run, even if a user has no sudo access. As a workaround, make sure that one's system does not contain any users with a specially crafted username. While this is the case and while untrusted users do not have the ability to create arbitrary users on the system, one should not be able to exploit this issue.


Severity



CVSS 3.x Severity and Metrics:

NIST CVSS score
NIST: NVD
Base Score:  8.1 HIGH
Vector:  CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

Nist CVSS score does not match with CNA score
CNA:  GitHub, Inc.
Base Score:  3.1 LOW
Vector:  CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:U/C:N/I:L/A:L


NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: It is possible that the NVD CVSS may not match that of the CNA. The most common reason for this is that publicly available information does not provide sufficient detail or that information simply was not available at the time the CVSS vector string was assigned.

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Hyperlink Resource
http://www.openwall.com/lists/oss-security/2023/11/02/1
https://ferrous-systems.com/blog/sudo-rs-audit/
https://github.com/memorysafety/sudo-rs/commit/bfdbda22968e3de43fa8246cab1681cfd5d5493d Patch 
https://github.com/memorysafety/sudo-rs/security/advisories/GHSA-2r3c-m6v7-9354 Vendor Advisory 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') cwe source acceptance level NIST   Provider acceptance level GitHub, Inc.  
CWE-23 Relative Path Traversal Provider acceptance level GitHub, Inc.  

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Change History

3 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2023-42456
NVD Published Date:
09/21/2023
NVD Last Modified:
11/03/2023
Source:
GitHub, Inc.