glibc unsetenv fails to properly handle environment variables passed more than once to a program

Overview

The glibc implementation of unsetenv() fails to properly remove one of two successive occurrences of the same environment variable if the variable is redundently passed to a program.

Description

The glibc implementation of unsetenv(), if called to remove an environment variable that occurs two times in succession on the environment variable list, will fail to remove one of the occurences due to an off-by-one error in the implementation.

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Impact

An attacker can pass multiple occurrences of a sensitive environment variable (such as LD_LIBRARY_PATH, LD_PRELOAD, etc.) to a setuid root program. Even if glibc forces that program to ignore these variables, they may be passed along to a program called from the setuid root program. Using this indirect execution, an attacker might cause malicious code to be executed as root.

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Solution

Apply vendor patches; see the Systems Affected section below.

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Vendor Information

846832

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Conectiva __ Affected

Notified: August 31, 2000 Updated: May 16, 2001

Status

Affected

Vendor Statement

<http://www.linuxsecurity.com/advisories/other_advisory-689.html&gt;

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%23846832 Feedback>).

Debian __ Affected

Notified: August 31, 2000 Updated: September 13, 2002

Status

Affected

Vendor Statement

<http://www.linuxsecurity.com/advisories/debian_advisory-683.html&gt;

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%23846832 Feedback>).

MandrakeSoft __ Affected

Notified: August 29, 2000 Updated: May 16, 2001

Status

Affected

Vendor Statement

<http://www.linuxsecurity.com/advisories/mandrake_advisory-667.html&gt;

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%23846832 Feedback>).

TurboLinux __ Affected

Notified: August 31, 2000 Updated: May 16, 2001

Status

Affected

Vendor Statement

<http://www.linuxsecurity.com/advisories/turbolinux_advisory-698.html&gt;

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%23846832 Feedback>).

CVSS Metrics

Group	Score	Vector
Base
Temporal
Environmental

References

• <http://www.securityfocus.com/bid/648&gt;
• <http://www.securityfocus.com/bid/1639&gt;

Acknowledgements

The original report of this vulnerability was by Tymm Twillman .

This document was last modified by Tim Shimeall.

Other Information

CVE IDs:	CVE-2000-0824
Severity Metric:	7.09 Date Public: