CVE-2002-1232 in ypserv
Summary
by MITRE
Memory leak in ypdb_open in yp_db.c for ypserv before 2.5 in the NIS package 3.9 and earlier allows remote attackers to cause a denial of service (memory consumption) via a large number of requests for a map that does not exist.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 07/18/2019
The vulnerability identified as CVE-2002-1232 represents a critical memory leak flaw within the ypserv NIS (Network Information Service) implementation that affected versions prior to 2.5 in the NIS package 3.9 and earlier. This issue resides in the ypdb_open function within the yp_db.c file, where improper memory management during the handling of non-existent map requests creates a persistent resource exhaustion condition. The flaw specifically manifests when remote attackers submit a large volume of requests targeting nonexistent NIS maps, leading to progressive memory consumption that eventually results in system instability and denial of service conditions.
The technical exploitation of this vulnerability leverages the fundamental design flaw in how ypserv processes map lookup requests for non-existent resources. When a client attempts to access a map that does not exist within the NIS database, the ypdb_open function fails to properly release allocated memory structures, causing memory leaks to accumulate with each failed request. This memory consumption pattern is particularly dangerous because it operates in a continuous loop where each unsuccessful lookup request compounds the existing memory pressure, creating a gradual but inevitable degradation of system performance. The vulnerability directly maps to CWE-401: Improper Release of Memory and falls under the broader category of resource management flaws that affect network services.
From an operational impact perspective, this vulnerability creates significant security implications for systems relying on NIS services for directory information and authentication. The memory leak can be exploited by attackers to consume system resources progressively, leading to complete system unresponsiveness or service interruption that affects legitimate users. Network administrators may observe increasing memory usage, system slowdowns, and potential service outages that can disrupt critical business operations. The vulnerability's remote exploitation capability means that attackers do not require local access to cause damage, making it particularly dangerous in networked environments where NIS services are exposed to external networks.
The attack vector for this vulnerability is straightforward and requires minimal technical expertise to execute effectively. Attackers can systematically send multiple requests for nonexistent NIS maps to the target system, causing memory consumption to grow continuously until system resources are exhausted. This type of attack aligns with the ATT&CK technique T1499.004: Endpoint Denial of Service, specifically targeting resource exhaustion through memory consumption. The vulnerability's impact is amplified in environments where NIS services are heavily utilized or where systems lack proper monitoring and resource limits to detect and prevent such gradual resource depletion attacks.
Mitigation strategies for CVE-2002-1232 focus primarily on upgrading to patched versions of the NIS package where the memory leak has been addressed. System administrators should immediately implement the vendor-provided security patches that correct the memory management issues in the ypdb_open function and ensure that all NIS servers are updated to versions 2.5 or later. Additionally, implementing network-level restrictions to limit NIS service access and monitoring memory consumption patterns can help detect and prevent exploitation attempts. Organizations should also consider implementing resource limits and process monitoring to identify abnormal memory usage that may indicate exploitation attempts. The remediation process must include thorough testing of updated systems to ensure that the patch does not introduce compatibility issues with existing NIS configurations and services.