Snort TCP Packet Reassembly Integer Overflow Vulnerability

Risk
High

Date Discovered
04-15-2003

Description
A vulnerability has been discovered in Snort. The problem occurs during the reassembly of TCP packets by the stream4 preprocesser. By sending specially crafted fragmented packets across a network monitored by Snort, it may be possible to trigger an integer overflow. As a result, a buffer overflow may occur, effectively allowing a remote attacker to corrupt heap memory.

Successful exploitation of this issue could allow a remote attacker to execute arbitrary code on a target system.

This issue effects Snort releases prior to Snort 2.0 RC1.

Platforms Affected
Conectiva Linux 8.0
Gentoo Linux 1.4 _rc2
Gentoo Linux 1.4 _rc3

Components Affected
SmoothWall SmoothWall 2.0 beta 4
Snort Project Snort 1.8
Snort Project Snort 1.8.1
Snort Project Snort 1.8.2
Snort Project Snort 1.8.3
Snort Project Snort 1.8.4
Snort Project Snort 1.8.5
Snort Project Snort 1.8.6
Snort Project Snort 1.8.7
Snort Project Snort 1.9
Snort Project Snort 1.9.1

Recommendations
Run all server processes as non-privileged users with minimal access rights.
Configure Snort to run with the least privileges necessary whenever possible. This may limit the consequences of an attacker executing arbitrary code on a target system.

Implement multiple redundant layers of security.
The exploitability of this issue to execute arbitrary code may be hindered through the use of various memory protection schemes. Where permissible, implement the use of non-executable and randomly mapped memory pages.

Implement multiple redundant layers of security.
Where possible, implement multiple layers of network security. This may limit the consequences of a network sensor or firewall from being made unavailable.

While NetBSD does not include Snort by default, Snort is available through pkgsrc. NetBSD users who have installed Snort packages should use pkgsrc/security/audit-packages to apply upgrades.

This issue is addressed in Snort 2.0. Users are advised to upgrade.

Fixes are available:

SmoothWall SmoothWall 2.0 beta 4:

Snort Project Snort 1.8:

Snort Project Snort 1.8.1:

Snort Project Snort 1.8.2:

Snort Project Snort 1.8.3:

Snort Project Snort 1.8.4:

Snort Project Snort 1.8.5:

Snort Project Snort 1.8.6:

Snort Project Snort 1.8.7:

Snort Project Snort 1.9:

Snort Project Snort 1.9.1:

References
Source: CERT CA-2003-13 Multiple Vulnerabilities in Snort Preprocessors
URL: http://online.securityfocus.com/advisories/5302

Source: CORE CORE-2003-0307 Snort TCP Stream Reassembly Integer Overflow Vulnerability
URL: http://online.securityfocus.com/advisories/5294

Source: Bug 2.0b4-mallard 005
URL: http://smoothwall.org/beta/bugs/mallard-006.html

Source: Snort Homepage
URL: http://www.snort.org/

Credits
Discovery of this issue is credited to Bruce Leidl, Juan Pablo Martinez Kuhn and Alejandro David Weil from Core Security Technologies.

Copyright (c) 2003 by Symantec Corp.
Permission to redistribute this alert electronically is granted as long as it is not edited in any way unless authorized by Symantec Security Response. Reprinting the whole or part of this alert in any medium other than electronically requires permission from symsecurity@symantec.com.

Disclaimer
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