Snort Information for VU#139129
Heap overflow in Snort "stream4" preprocessor
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Snort(TM) Advisory: Integer Overflow in Stream4
Date: April 16, 2003
All versions of the following products are affected:
* Snort 1.8 through 1.9.1
* Snort CVS - current branch up to version 2.0.0 beta
The Sourcefire Vulnerability Research Team has learned of an integer overflow
in the Snort stream4 preprocessor used by the Sourcefire Network Sensor
product line. The Snort stream4 preprocessor (spp_stream4) incorrectly
calculates segment size parameters during stream reassembly for certain
sequence number ranges which can lead to an integer overflow that can be
expanded to a heap overflow.
The Snort stream4 flaw may lead to a denial of service (DoS) attack or
remote command execution on a host running Snort. This attack can be launched
by crafting TCP stream packets and transmitting them over a network segment
that is being monitored by a vulnerable Snort implementation. In its
default configuration, certain versions of snort are vulnerable to this
attack, as is the default configuration of the Snort IDS.
Disabling the stream4 preprocessor will make the snort invulnerable to the
To disable the stream4 preprocessor, edit snort.conf and replace any lines
that begin with "preprocessor stream4" with "# preprocessor stream4"
NOTE: Disabling the stream4 preprocessor disables stateful inspection and
stream reassembly and could allow someone to evade snort using tcp stream
Snort 2.0 has been released and corrects this vulnerability.
(C) 2003 Sourcefire, Inc. All rights reserved.
Sourcefire and Snort are trademarks or registered trademarks of Sourcefire, INC.
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The vendor has not provided us with any further information regarding this vulnerability.
Snort has released version 2.0 to address this vulnerability. This version is available at