Title: Snort TCP Packet Reassembly Integer Overflow Vulnerability
Severity: CRITICAL
Description:
Snort is a freely available, open source intrusion detection system. It is available for Unix, Linux, and Microsoft Windows platforms.
The stream4 preprocessor is designed to reassemble fragmented TCP packets before passing them to Snort for analysis. It is also designed to detect various IDS evasion attacks.
A vulnerability has been discovered in the stream4 preprocessor which may allow an attacker to execute arbitrary code with the privileges of Snort.
The problem occurs in the Traversefunc() function, located in the spp_stream4.c source file, while carrying out various sanity checks. Specifically, an integer overflow may occur while making a bounds check, which could result in a potential heap overflow going undetected.
The integer overflow can be triggered by passing fragmented TCP packets across a network monitored by Snort which contain specially calculated sequence and acknowledgement values. The sequence numbers must be a large enough value so that, when added to the packet size, a 32 bit calculation integer will overflow. When these values are later calculated during a check for potential memory corruption, the integer overflow will trigger a miscalculation where an exception would typically be triggered.
When memcpy() is later called to copy the data to a heap buffer, the previously undetected overflow will occur. This may allow an attacker to corrupt heap memory.
Successful exploitation of this issue may allow an attacker to overwrite sensitive heap memory with malicious values. By overwriting a function pointer or corrupting memory management headers, it may be possible to leverage this vulnerability to execute arbitrary code.
This issue effects Snort releases prior to Snort 2.0 RC1.
Affected Products:
- Conectiva Linux 8.0.0
- Debian Linux 3.0.0
- Debian Linux 3.0.0 alpha
- Debian Linux 3.0.0 arm
- Debian Linux 3.0.0 hppa
- Debian Linux 3.0.0 ia-32
- Debian Linux 3.0.0 ia-64
- Debian Linux 3.0.0 m68k
- Debian Linux 3.0.0 mips
- Debian Linux 3.0.0 mipsel
- Debian Linux 3.0.0 ppc
- Debian Linux 3.0.0 s/390
- Debian Linux 3.0.0 sparc
- Gentoo Linux 1.4.0 _rc2
- Gentoo Linux 1.4.0 _rc3
- MandrakeSoft Corporate Server 2.1.0
- MandrakeSoft Linux Mandrake 8.2.0
- MandrakeSoft Linux Mandrake 8.2.0 ppc
- MandrakeSoft Linux Mandrake 9.0.0
- MandrakeSoft Linux Mandrake 9.1.0
- MandrakeSoft Linux Mandrake 9.1.0 ppc
- MandrakeSoft Multi Network Firewall 2.0.0
- SmoothWall SmoothWall 2.0.0 Beta 4
- Snort Project Snort 1.8.0
- 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 1.8.4 beta1
- Snort Project Snort 1.8.5
- Snort Project Snort 1.8.6
- Snort Project Snort 1.8.7
- Snort Project Snort 1.9.0
- Snort Project Snort 1.9.1
References:
- CORE Security: Snort TCP Stream Integer Overflow
- Conectiva: CLSA-2003:671
- SmoothWall: Bug 2.0b4-mallard 005
- Snort: Snort Homepage
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