Debian glibc 2 symlink issue could allow arbitrary file overwriting

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.

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Impact

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

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Solution

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

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Vendor Information

664141

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Debian Affected

Notified: May 25, 2001 Updated: June 08, 2001

Status

Affected

Vendor Statement

We have not received a statement from the vendor.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us [email](<mailto:[email protected]?Subject=VU%23664141 Feedback>).

CVSS Metrics

Group	Score	Vector
Base
Temporal
Environmental

References

<http://www.securityfocus.com/bid/1719&gt;

Acknowledgements

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
Severity Metric:	0.11 Date Public: