CVE-2015-3246

Impact:
Important
Public Date:
2015-07-23
IAVA:
2015-A-0179
Bugzilla:
1233052: CVE-2015-3246 libuser: Security flaw in handling /etc/passwd file
A flaw was found in the way the libuser library handled the /etc/passwd file. A local attacker could use an application compiled against libuser (for example, userhelper) to manipulate the /etc/passwd file, which could result in a denial of service or possibly allow the attacker to escalate their privileges to root.

Find out more about CVE-2015-3246 from the MITRE CVE dictionary dictionary and NIST NVD.

Statement

This issue affects the versions of libuser as shipped with Red Hat Enterprise Linux 5. Red Hat Enterprise Linux 5 is now in Production 3 Phase of the support and maintenance life cycle. This vulnerability has been rated as having Important security impact and is not currently planned to be addressed in future updates. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.

CVSS v2 metrics

Base Score 6.8
Base Metrics AV:L/AC:L/Au:S/C:C/I:C/A:C
Access Vector Local
Access Complexity Low
Authentication Single
Confidentiality Impact Complete
Integrity Impact Complete
Availability Impact Complete

Find out more about Red Hat support for the Common Vulnerability Scoring System (CVSS).

Red Hat Security Errata

Platform Errata Release Date
Red Hat Enterprise Linux 7 (libuser) RHSA-2015:1483 2015-07-23
Red Hat Enterprise Linux 6 (libuser) RHSA-2015:1482 2015-07-23

Affected Packages State

Platform Package State
Red Hat Enterprise Linux 5 libuser Will not fix

Acknowledgements

Red Hat would like to thank Qualys for reporting this issue.

Mitigation

Add pam_warn and pam_deny rules to /etc/pam.d/chfn and /etc/pam.d/chsh to prevent non-root users from using this functionality. With these edits, the files should contain:

auth sufficient pam_rootok.so
auth required pam_warn.so
auth required pam_deny.so
auth include system-auth
account include system-auth
password include system-auth
session include system-auth

After these changes, attempts by unprivileged users to use chfn and chsh (and the respective functionality in the userhelper program) will fail, and will be logged (by default in /var/log/secure).

External References

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