Vulnerability Note VU#664141

Debian glibc 2 symlink issue could allow arbitrary file overwriting

Original Release date: 24 Jul 2001 | Last revised: 31 Jul 2001

Overview

Some versions of ld.so, the loader for shared libraries in UNIX/LINUX, do not properly clear risky environment variables, allowing a symlink attack to overwrite arbitrary files.

Description

LD_DEBUG_OUTPUT specifies a directory in which ld.so creates a file with a predictable name based on the process ID. ld.so uses this file to store debugging information. The current version of ld.so does not unset the environment variable LD_DEBUG_OUTPUT prior to calling setuid root programs. Even though setuid root programs are forced to ignore the LD_DEBUG_OUTPUT variable, output would be generated there by programs called from setuid root programs.

Impact

By setting up appropriate symlinks, a malicious user could cause arbitrary files to be overwritten with debugging information.

Solution

Pending patch information by the vendor, CERT/CC is unaware of a practical solution to this problem.

Systems Affected (Learn More)

VendorStatusDate NotifiedDate Updated
DebianAffected25 May 200108 Jun 2001
If you are a vendor and your product is affected, let us know.

CVSS Metrics (Learn More)

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A N/A

References

Credit

The original report of this vulnerabilty was by Jakub Vlasek .

This document was last modifed by Tim Shimeall.

Other Information

  • CVE IDs: CVE-2000-0959
  • Date Public: 26 Sep 2000
  • Date First Published: 24 Jul 2001
  • Date Last Updated: 31 Jul 2001
  • Severity Metric: 0.11
  • Document Revision: 8

Feedback

If you have feedback, comments, or additional information about this vulnerability, please send us email.