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CERT Coordination Center


BSD libc contains a buffer overflow vulnerability in link_ntoa()

Vulnerability Note VU#548487

Original Release Date: 2016-12-06 | Last Revised: 2016-12-08

Overview

The BSD libc library's link_ntoa() function may be vulnerable to a classic buffer overflow. It is currently unclear if this issue is exploitable.

Description

CWE-120: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') - CVE-2016-6559

Improper bounds checking of the obuf variable in the link_ntoa() function in linkaddr.c may allow an attacker to read or write from memory.

The full impact and severity depends on the method of exploit and how the library is used by applications. According to analysis by FreeBSD developers, it is very unlikely that applications exist that utilize link_ntoa() in an exploitable manner, and the CERT/CC is not aware of any proof of concept. A blog post describes the functionality of link_ntoa() and points out that none of the base utilities use this function in an exploitable manner. For more information, please see FreeBSD Security Advisory SA-16:37.

The CVSS score below reflects a worst-case scenario in which an attacker may execute arbitrary code with root permissions. It is unclear if any program exists that would allow exploit in any manner.

Impact

The full impact and severity depends on the method of exploit and how the library is used by applications. An attacker may be able to execute arbitrary code, but CERT/CC is currently unaware of a proof of concept.

Solution

Apply an update

FreeBSD libc was updated to address this vulnerability. Affected users are encouraged to upgrade to the latest version of libc and/or the latest release of your operating system.

In FreeBSD, the following patch levels (or later) contain a fix:

9.3-RELEASE-p51
10.1-RELEASE-p43
10.2-RELEASE-p26
10.3-RELEASE-p13
11.0-RELEASE-p4

Vendor Information

548487
Expand all

Apple

Notified:  October 10, 2016 Updated:  November 16, 2016

Status

  Affected

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

We are not aware of further vendor information regarding this vulnerability.

Addendum

There are no additional comments at this time.

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

FreeBSD Project

Notified:  October 21, 2016 Updated:  November 21, 2016

Statement Date:   November 21, 2016

Status

  Affected

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

In FreeBSD, the following patch levels (or later) contain a fix:

9.3-RELEASE-p51
10.1-RELEASE-p43
10.2-RELEASE-p26
10.3-RELEASE-p13
11.0-RELEASE-p4

Addendum

There are no additional comments at this time.

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

HardenedBSD

Notified:  October 26, 2016 Updated:  December 07, 2016

Statement Date:   December 07, 2016

Status

  Affected

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

HardenedBSD has fixed this issue in the latest releases. Please see the commit URLs below.

Vendor References

https://github.com/HardenedBSD/hardenedBSD-stable/releases/tag/HardenedBSD-10-STABLE-v46.20 https://github.com/HardenedBSD/hardenedBSD-stable/releases/tag/HardenedBSD-11-STABLE-v46.11

Addendum

There are no additional comments at this time.

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

NetBSD

Notified:  October 26, 2016 Updated:  December 08, 2016

Statement Date:   December 08, 2016

Status

  Affected

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

NetBSD has updated on 20161207 to address this issue.

Addendum

There are no additional comments at this time.

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

DesktopBSD

Notified:  October 26, 2016 Updated:  October 26, 2016

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Addendum

There are no additional comments at this time.

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

DragonFly BSD Project

Notified:  October 26, 2016 Updated:  October 26, 2016

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Addendum

There are no additional comments at this time.

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

F5 Networks, Inc.

Notified:  October 26, 2016 Updated:  October 26, 2016

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Addendum

There are no additional comments at this time.

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

Juniper Networks

Notified:  October 26, 2016 Updated:  October 26, 2016

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Addendum

There are no additional comments at this time.

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

Nokia

Notified:  October 26, 2016 Updated:  October 26, 2016

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Addendum

There are no additional comments at this time.

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

OpenBSD

Notified:  October 26, 2016 Updated:  December 08, 2016

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

OpenBSD shares the same affected code, see below:

Vendor References

http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/lib/libc/net/linkaddr.c?sortby=date

Addendum

There are no additional comments at this time.

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

PC-BSD

Notified:  November 16, 2016 Updated:  November 16, 2016

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Addendum

There are no additional comments at this time.

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

QNX Software Systems Inc.

Notified:  October 26, 2016 Updated:  October 26, 2016

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Addendum

There are no additional comments at this time.

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

TrueOS

Notified:  November 16, 2016 Updated:  November 16, 2016

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

We are not aware of further vendor information regarding this vulnerability.

Addendum

There are no additional comments at this time.

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


CVSS Metrics

Group Score Vector
Base 9.3 AV:N/AC:M/Au:N/C:C/I:C/A:C
Temporal 6.9 E:U/RL:OF/RC:C
Environmental 1.7 CDP:ND/TD:L/CR:ND/IR:ND/AR:ND

References

Credit

Thanks to the reporter who wishes to remain anonymous.

This document was written by Garret Wassermann.

Other Information

CVE IDs: CVE-2016-6559
Date Public: 2016-12-06
Date First Published: 2016-12-06
Date Last Updated: 2016-12-08 22:54 UTC
Document Revision: 53

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