Debian DSA-3659-1 : linux - security update

Medium Nessus Plugin ID 93324

Synopsis

The remote Debian host is missing a security-related update.

Description

Several vulnerabilities have been discovered in the Linux kernel that may lead to a privilege escalation, denial of service or have other impacts.

- CVE-2016-5696 Yue Cao, Zhiyun Qian, Zhongjie Wang, Tuan Dao, and Srikanth V. Krishnamurthy of the University of California, Riverside; and Lisa M. Marvel of the United States Army Research Laboratory discovered that Linux's implementation of the TCP Challenge ACK feature results in a side channel that can be used to find TCP connections between specific IP addresses, and to inject messages into those connections.

Where a service is made available through TCP, this may allow remote attackers to impersonate another connected user to the server or to impersonate the server to another connected user. In case the service uses a protocol with message authentication (e.g. TLS or SSH), this vulnerability only allows denial of service (connection failure). An attack takes tens of seconds, so short-lived TCP connections are also unlikely to be vulnerable.

This may be mitigated by increasing the rate limit for TCP Challenge ACKs so that it is never exceeded: sysctl net.ipv4.tcp_challenge_ack_limit=1000000000

- CVE-2016-6136 Pengfei Wang discovered that the audit subsystem has a 'double-fetch' or 'TOCTTOU' bug in its handling of special characters in the name of an executable. Where audit logging of execve() is enabled, this allows a local user to generate misleading log messages.

- CVE-2016-6480 Pengfei Wang discovered that the aacraid driver for Adaptec RAID controllers has a 'double-fetch' or 'TOCTTOU' bug in its validation of 'FIB' messages passed through the ioctl() system call. This has no practical security impact in current Debian releases.

- CVE-2016-6828 Marco Grassi reported a 'use-after-free' bug in the TCP implementation, which can be triggered by local users.
The security impact is unclear, but might include denial of service or privilege escalation.

Solution

Upgrade the linux packages.

For the stable distribution (jessie), these problems have been fixed in version 3.16.36-1+deb8u1. In addition, this update contains several changes originally targeted for the upcoming jessie point release.

See Also

https://security-tracker.debian.org/tracker/CVE-2016-5696

https://security-tracker.debian.org/tracker/CVE-2016-6136

https://security-tracker.debian.org/tracker/CVE-2016-6480

https://security-tracker.debian.org/tracker/CVE-2016-6828

https://packages.debian.org/source/jessie/linux

https://www.debian.org/security/2016/dsa-3659

Plugin Details

Severity: Medium

ID: 93324

File Name: debian_DSA-3659.nasl

Version: 2.7

Type: local

Agent: unix

Published: 2016/09/06

Updated: 2018/11/10

Dependencies: 12634

Risk Information

Risk Factor: Medium

CVSS v2.0

Base Score: 5.8

Temporal Score: 4.5

Vector: CVSS2#AV:N/AC:M/Au:N/C:N/I:P/A:P

Temporal Vector: CVSS2#E:POC/RL:OF/RC:C

CVSS v3.0

Base Score: 5.5

Temporal Score: 5

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:debian:debian_linux:linux, cpe:/o:debian:debian_linux:8.0

Required KB Items: Host/local_checks_enabled, Host/Debian/release, Host/Debian/dpkg-l

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 2016/09/04

Reference Information

CVE: CVE-2016-5696, CVE-2016-6136, CVE-2016-6480, CVE-2016-6828

DSA: 3659