Linux Kernel TCP Sequence Number Generation Security Weakness

This script is Copyright (C) 2011-2014 Tenable Network Security, Inc.


Synopsis :

It may be possible to predict TCP/IP Initial Sequence Numbers for the
remote host.

Description :

The Linux kernel is prone to a security weakness related to TCP
sequence number generation. Attackers can exploit this issue to inject
arbitrary packets into TCP sessions using a brute-force attack.

An attacker may use this vulnerability to create a denial of service
condition or a man-in-the-middle attack.

Note that this plugin may fire as a result of a network device (such
as a load balancer, VPN, IPS, transparent proxy, etc.) that is
vulnerable and that re-writes TCP sequence numbers, rather than the
host itself being vulnerable.

See also :

http://lwn.net/Articles/455135/
http://www.nessus.org/u?9881d9af

Solution :

Contact the OS vendor for a Linux kernel update / patch.

Risk factor :

Medium / CVSS Base Score : 6.8
(CVSS2#AV:N/AC:M/Au:N/C:P/I:P/A:P)
CVSS Temporal Score : 5.9
(CVSS2#E:ND/RL:OF/RC:C)
Public Exploit Available : true

Family: General

Nessus Plugin ID: 56283 ()

Bugtraq ID: 49289

CVE ID: CVE-2011-3188