INFORMATION BULLETIN
INFORMATION BULLETIN
| PROBLEM: | An exploitable heap overflow in the stream4 preprocessor module resulting from sequence number calculations that overflow a 32 bit integer variable has been discovered. |
| AFFECTED SOFTWARE: | Snort 2.0.0 beta version Snort 1.9.x Snort 1.8.x |
| DAMAGE: | A remote attacker could possibly execute arbitrary commands on a system running the Snort sensor with the privileges of the user running the Snort process (usually root), execute a denial of service attack against the Snort sensor, and possibly use IDS evasion techniques that would prevent the sensor from detecting attacks on a monitored network. |
| SOLUTION: | Upgrade to Snort v2.0 released on April 14, 2003. |
| VULNERABILITY ASSESSMENT: |
The risk is HIGH. A remote attacker does not need to know on which host the Snort sensor is running. To successfully exploit this vulnerability, it would only be necessary to guess where to send traffic that the Snort sensor will 'see' and analyze. Then an integer overflow could possibly be designed to occur while making a bounds check, which could result in a potential heap overflow going undetected. |
| LINKS: | |
| CIAC BULLETIN: | http://www.ciac.org/ciac/bulletins/n-078.shtml |
| ORIGINAL BULLETIN: | http://www.snort.org/advisories/snort-2003-04-16-1.txt |
| PATCHES: | http://www.snort.org/ |
[***** Start Snort(TM) Advisory: Integer Overflow in Stream4 *****] -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Snort(TM) Advisory: Integer Overflow in Stream4 Date: April 16, 2003 Affected Versions: 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 Synopsis: 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 attack. 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 segmentation attacks. Patches: 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. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.1 (GNU/Linux) iD8DBQE+nadjavJ5BgQ0p28RAi8FAKCviv78UU8V2k+smfZU875Lcrhb9gCfQIXK CuzzM4EKTvbvkvo+wL47YYM= =u1yD -----END PGP SIGNATURE----- [***** End Snort(TM) Advisory: Integer Overflow in Stream4 *****]
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