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From:	nnposter_(at)_disclosed.not <nnposter_(at)_disclosed.not>
Date:	19.05.2007
Subject:	Predictable TCP ISN in Packeteer PacketShaper

Predictable TCP ISN in Packeteer PacketShaper


Critical: Less critical
Impact: Connection spoofing, DoS
Where: Local network

Product: Packeteer PacketShaper
http://www.packetshaper.com/


Description: The TCP/IP stack of Packeteer PacketShaper is generating predictable initial sequence numbers (ISN): The sequence number is incremented by 128000 per second and by 64000 per connection. (As an example, if the current SYN/ACK ISN is 319104000 then about six seconds later the ISN is likely to be 319936000.) This allows an attacker to spoof connections from trusted clients or launch a DoS attack.


This type of vulnerability has been described over ten years ago in:

* CERT Advisory CA-1995-01
 http://www.cert.org/advisories/CA-1995-01.html

* RFC 1948
 http://www.faqs.org/rfcs/rfc1948.html


The vulnerability has been identified in versions 7.3.0g2 and 7.5.0g1. However, other versions may be also affected.


Solution:
Restrict network access to the device management interfaces


Found by:
nnposter