Vulnerability Note VU#175500

Snort is an open-source intrusion detection system (IDS). A lack of validation on attacker-controlled data may allow a buffer overflow to occur in the in Snort Back Orifice preprocessor. A remote, unauthenticated attacker may be able to trigger the buffer overflow by sending a specially crafted Back Orifice ping to a vulnerable Snort installation.

To exploit this vulnerability, an attacker does not need to send packets directly to the Snort sensor. It is sufficient to send packets to any of the hosts on the network monitored by Snort.

A remote attacker can execute arbitrary code with the privileges of the Snort process, typically root or SYSTEM.

Update

This issue has been addressed in Snort version 2.4.3.

Disable Snort Back Orifice preprocessor

Disabling the Snort Back Orifice preprocessor will mitigate this vulnerability. However, without the Snort preprocessor, the Snort sensor will not detect or prevent Back Orifice traffic. Snort suggests the following steps to disable the Back Orifice preprocessor:

The Back Orifice preprocessor can be disabled by commenting out the line "preprocessor bo" in snort.conf. This can be done in any text editor using the following procedure:

1. Locate the line "preprocessor bo"
2. Comment out this line by preceding it with a hash (#). The new line will look like "#preprocessor bo"
3. Save the file
4. Restart snort