CVE-2010-0751 in libnids
Summary
by MITRE
The ip_evictor function in ip_fragment.c in libnids 1.24, as used in dsniff and possibly other products, allows remote attackers to cause a denial of service (NULL pointer dereference and crash) via crafted fragmented packets.
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Analysis
by VulDB Data Team • 03/14/2025
The vulnerability identified as CVE-2010-0751 represents a critical denial of service flaw within the libnids library version 1.24, which serves as a foundational component for network packet analysis tools including dsniff. This vulnerability manifests specifically within the ip_evictor function located in the ip_fragment.c source file, demonstrating how improper handling of network packet fragments can lead to system instability. The flaw exists in the manner in which the library processes fragmented IP packets, creating a scenario where maliciously crafted packets can trigger unexpected behavior in applications that depend on this library.
The technical implementation of this vulnerability stems from a null pointer dereference condition that occurs when the ip_evictor function attempts to process fragmented network packets without proper validation of packet structure or fragment state. When attackers send specially crafted fragmented packets to a system running software that utilizes libnids 1.24, the function fails to adequately check for null pointers before attempting to dereference them, resulting in a segmentation fault that crashes the affected application. This behavior aligns with CWE-476 which categorizes null pointer dereference vulnerabilities as a common class of software defects that can lead to system crashes and potential privilege escalation scenarios.
The operational impact of CVE-2010-0751 extends beyond simple service disruption, as it affects the reliability and availability of network monitoring and analysis tools that form the backbone of many security operations. Systems utilizing dsniff or similar packet capture and analysis applications become vulnerable to remote exploitation, allowing attackers to disrupt network monitoring capabilities without requiring elevated privileges or complex attack chains. The vulnerability demonstrates how fundamental network protocol handling functions can become attack vectors when proper input validation and error handling mechanisms are absent from the codebase.
Security practitioners should consider this vulnerability in the context of the ATT&CK framework's privilege escalation and denial of service tactics, where the null pointer dereference represents a primitive that can be leveraged to achieve system instability. The vulnerability's exploitation requires minimal skill and resources, making it particularly dangerous for environments where network monitoring tools are deployed. Organizations using affected software should prioritize patching and updating their libnids installations to versions that address this specific null pointer dereference issue. The remediation process involves upgrading to libnids 1.25 or later versions where the ip_evictor function has been properly hardened against malformed packet inputs, including comprehensive validation of fragment headers and proper null pointer checks before memory access operations. Additionally, network administrators should implement monitoring solutions that can detect unusual packet patterns and potential exploitation attempts, as the vulnerability may be used as part of broader attack campaigns targeting network infrastructure components.