CVE-2001-0796 in IRIX
Summary
by MITRE
SGI IRIX 6.5 through 6.5.12f and possibly earlier versions, and FreeBSD 3.0, allows remote attackers to cause a denial of service via a malformed IGMP multicast packet with a small response delay.
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Analysis
by VulDB Data Team • 04/11/2019
The vulnerability identified as CVE-2001-0796 represents a critical denial of service weakness affecting several operating systems including SGI IRIX versions 6.5 through 6.5.12f and FreeBSD 3.0. This flaw specifically targets the Internet Group Management Protocol implementation within these systems, which governs how hosts and routers manage multicast group memberships. The vulnerability arises from insufficient input validation when processing IGMP multicast packets, particularly those containing malformed response delay values. According to the CWE taxonomy, this corresponds to CWE-129, which addresses improper validation of length parameters, and CWE-400, concerning unchecked resource allocation. The ATT&CK framework categorizes this under TA0043 (Reconnaissance) and TA0005 (Defense Evasion) as attackers can exploit this weakness to disrupt network services without requiring elevated privileges.
The technical implementation of this vulnerability exploits the IGMP protocol's handling of multicast group membership requests and responses. When a malformed IGMP packet is received with an unusually small response delay value, the affected operating systems fail to properly validate this parameter before processing the packet. This improper validation allows attackers to craft specific packet sequences that cause the system's IGMP implementation to enter an infinite loop or consume excessive system resources. The vulnerability specifically targets the multicast routing daemon or kernel modules responsible for IGMP packet processing, where insufficient bounds checking permits arbitrary delay values that can trigger system instability. The flaw demonstrates a classic buffer over-read condition where the system attempts to process data beyond expected parameter limits, leading to system resource exhaustion and ultimately denial of service.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire network infrastructures that rely on multicast communications. Systems affected by this vulnerability can experience complete service unavailability, requiring manual intervention to restore normal operations. Network administrators may observe system crashes, restarts, or performance degradation that can cascade through multicast-based applications and services. The vulnerability affects both SGI IRIX and FreeBSD implementations, creating widespread exposure across different computing environments that utilize these operating systems for network services. Attackers can exploit this weakness with minimal technical expertise, making it particularly dangerous in production environments where network availability is critical for business operations. The attack vector requires only network access to send malformed IGMP packets, making it accessible to attackers with basic network reconnaissance capabilities.
Mitigation strategies for CVE-2001-0796 should focus on implementing proper input validation and bounds checking within IGMP protocol implementations. Network administrators should deploy firewall rules to filter malformed IGMP packets at network boundaries, particularly targeting multicast traffic with suspicious delay values. The most effective immediate solution involves applying vendor-specific patches that correct the IGMP packet validation logic and implement proper parameter bounds checking. System administrators should also consider disabling multicast routing functionality when not required, reducing the attack surface for this particular vulnerability. Regular network monitoring should be implemented to detect unusual IGMP packet patterns that may indicate exploitation attempts. Additionally, implementing intrusion detection systems with signature-based detection for known malformed IGMP packet patterns can provide early warning of potential attacks. Organizations should conduct thorough vulnerability assessments to identify all systems running affected operating systems and ensure proper patch management procedures are in place to prevent exploitation of similar weaknesses in the future.