Title: Snort ICMP Denial of Service Vulnerability
Severity: HIGH
Description:
Snort is a network intrusion detection system (NIDS). It was originally written for Linux and Unix systems, although it has also been ported to run under Microsoft Windows. Snort is capable of flexible and powerful content analysis of network traffic, and can detect a large number of attack attempts.
A vulnerability exists in some versions of Snort. If a maliciously constructed ICMP packet is received by the snort daemon, the process will crash. A restart will be required to regain normal functionality.
The flaw lies in the handling of ICMP packets. ICMP packets contain header information within the packet data seqment, in addition to the IP header. A minimal four byte header is defined for all ICMP packets, and additional header information may be included, dependent on the ICMP type.
ICMP Echo Request packets are used by the ping program. These ICMP packets define eight bytes of header information in addition to the IP header, and may include additional information within the data section of the ICMP packet. Vulnerable versions of Snort define the length of the ICMP header to be eight bytes, which properly handles this case.
However, it is possible to form a packet with a minimal four byte ICMP header, and an ICMP type indicating is is an echo request packet. If this is sent to a vulnerable snort daemon, the process will crash.
Affected Products:
- Snort Project Snort 1.8.3
References:
- Martin Roesch: Snort Homepage
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