Linux kernel does not properly validate user input via sysctl for negative value

Overview

Unprivileged local users can exploit the sysctl Linux kernel program to gain privileged access.

Description

A program called sysctl in the Linux kernel allows a privileged local user to read or write runtime system settings. Unprivileged local users are also allowed to use sysctl to read many of these settings. The program takes as parameters a buffer location and length. The length parameter is declared as signed and, therefore, allows passing of negative values. According to Chris Evans, the discoverer of this vulnerability, “by specifying a negative buffer length, a user can read pretty arbitrary memory.” This flaw allows attackers to read privileged Linux kernel memory and, ultimately, gain root access. Linux kernel version 2.2.18 or before are vulnerable to this flaw. Any Linux product that is dependent on this kernel is, therefore, vulnerable.

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Impact

Unprivileged local users can read privileged kernel space addresses and, potentially, gain privileged (root) access.

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Solution

Upgrade the Linux kernel to version 2.2.19 or later. The release notes for Linux 2.2.19 at <http://www.linux.org.uk/VERSION/relnotes.2219.html&gt; describe the security fix. For users of specific Linux vendors, use the vendor-specific upgrades for convenience and consistency.

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Vendor Information

698640

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Caldera __ Affected

Notified: February 08, 2001 Updated: June 26, 2001

Status

Affected

Vendor Statement

Caldera’s fix for this vulnerability is at <http://www.caldera.com/support/security/advisories/CSSA-2001-009.0.txt&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%23698640 Feedback>).

Conectiva __ Affected

Notified: April 19, 2001 Updated: June 26, 2001

Status

Affected

Vendor Statement

Conectiva’s fix for this vulnerability is at http://distro.conectiva.com/atualizacoes/?id=a&anuncio=000394.

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%23698640 Feedback>).

Debian __ Affected

Notified: April 16, 2001 Updated: June 26, 2001

Status

Affected

Vendor Statement

Debian’s fix for this vulnerability is at <http://www.debian.org/security/2001/dsa-047&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%23698640 Feedback>).

Immunix __ Affected

Notified: February 08, 2001 Updated: June 26, 2001

Status

Affected

Vendor Statement

Immunix’s fix for this vulnerability is at <http://download.immunix.org/ImmunixOS/7.0-beta/updates/IMNX-2001-70-002-01&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%23698640 Feedback>).

MandrakeSoft __ Affected

Notified: April 17, 2001 Updated: June 26, 2001

Status

Affected

Vendor Statement

MandrakeSoft’s fix for this vulnerability is at <http://www.linux-mandrake.com/en/updates/2001/MDKSA-2001-037.php3?dis=7.0&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%23698640 Feedback>).

RedHat __ Affected

Notified: February 08, 2001 Updated: June 26, 2001

Status

Affected

Vendor Statement

Red Hat provides fixes to this vulnerability at either <http://www.redhat.com/support/errata/RHSA-2001-013.html&gt; or <http://www.redhat.com/support/errata/RHSA-2001-047.html&gt;. The latter link is their most recent word on this vulnerability.

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%23698640 Feedback>).

SuSE __ Affected

Notified: May 17, 2001 Updated: June 26, 2001

Status

Affected

Vendor Statement

SuSE’s fix for this vulnerability is at <http://www.securityfocus.com/archive/1/185199&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%23698640 Feedback>).

Trustix __ Affected

Notified: February 13, 2001 Updated: June 26, 2001

Status

Affected

Vendor Statement

Trustix’s fix for this vulnerability is at <http://archives.neohapsis.com/archives/bugtraq/2001-02/0267.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%23698640 Feedback>).

Slackware __ Unknown

Updated: July 18, 2001

Status

Unknown

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

BugTraq reported Slackware Linux vulnerable to this flaw at <http://www.securityfocus.com/bid/2364&gt;. The CERT/CC has no additional information at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us [email](<mailto:[email protected]?Subject=VU%23698640 Feedback>).

CVSS Metrics

Group	Score	Vector
Base
Temporal
Environmental

References

• <http://www.securityfocus.com/archive/59/162008&gt;
• <http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2001-0316&gt;
• <http://www.securityfocus.com/bid/2364&gt;
• <http://www.redhat.com/support/errata/RHSA-2001-013.html&gt;
• <http://www.redhat.com/support/errata/RHSA-2001-047.html&gt;
• <http://www.ciac.org/ciac/bulletins/l-045.shtml&gt;
• <http://www.caldera.com/support/security/advisories/CSSA-2001-009.0.txt&gt;
• <http://www.debian.org/security/2001/dsa-047&gt;
• <http://www.linux.org.uk/VERSION/relnotes.2219.html&gt;
• <http://www.linux-mandrake.com/en/updates/2001/MDKSA-2001-037.php3?dis=7.0&gt;
• <http://download.immunix.org/ImmunixOS/7.0-beta/updates/IMNX-2001-70-002-01&gt;
• <http://www.securityfocus.com/archive/1/161568&gt;
• <http://www.securityfocus.com/archive/1/185199&gt;
• <http://archives.neohapsis.com/archives/bugtraq/2001-02/0267.html&gt;
• http://distro.conectiva.com/atualizacoes/?id=a&anuncio=000394

Acknowledgements

Thanks to Chris Evans for discovering this vulnerability.

This document was written by Andrew P. Moore.

Other Information

CVE IDs:	CVE-2001-0316
Severity Metric:	9.22 Date Public: