CVE-2011-1680 in ncpfs
Summary
by MITRE
ncpmount in ncpfs 2.2.6 and earlier does not remove the /etc/mtab~ lock file after a failed attempt to add a mount entry, which has unspecified impact and local attack vectors.
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Analysis
by VulDB Data Team • 11/02/2021
The vulnerability identified as CVE-2011-1680 resides within the ncpmount utility of ncpfs version 2.2.6 and earlier, representing a critical flaw in the Network Computing Protocol filesystem implementation. This issue manifests when the ncpmount utility fails to properly clean up temporary lock files during mount operations, specifically leaving behind the /etc/mtab~ file which serves as a synchronization mechanism for mount table updates. The failure to remove this lock file creates a persistent state that can interfere with subsequent mount operations and system resource management.
The technical root cause of this vulnerability stems from inadequate error handling within the ncpmount utility's mount entry addition process. When a mount operation fails for any reason, whether due to network connectivity issues, authentication failures, or permission problems, the utility correctly identifies the failure but fails to execute the cleanup routine responsible for removing the /etc/mtab~ lock file. This behavior creates a race condition and resource contention scenario where the lock file remains in place, potentially blocking legitimate mount operations and creating inconsistencies in the system's mount table management. The vulnerability aligns with CWE-362, which describes Concurrent Execution using Shared Resource with Improper Synchronization, and represents a classic case of resource leak in a multi-threaded or multi-process environment.
From an operational perspective, this vulnerability presents multiple attack vectors and impact scenarios that can significantly compromise system stability and security. Local attackers can exploit this flaw to cause denial of service conditions by repeatedly attempting failed mount operations, thereby accumulating lock files that eventually exhaust available system resources or create mount table corruption. The unspecified impact mentioned in the CVE description suggests that the consequences could range from simple service disruption to more severe system instability, potentially allowing attackers to manipulate the mount table in ways that could affect other system components or create unauthorized access points. The local attack vector indicates that exploitation requires physical or network access to the target system, but once achieved, the impact can be substantial in environments where network filesystem access is frequently used.
The security implications extend beyond simple denial of service, as this vulnerability can be leveraged in combination with other attack vectors to create more complex exploitation scenarios. System administrators may find that their mount table becomes increasingly corrupted over time due to repeated failed mount attempts, leading to unpredictable behavior in applications that depend on proper filesystem mounting. The persistent nature of the lock file also means that legitimate mount operations may fail or behave unpredictably until the lock file is manually removed, creating a maintenance burden and potential security risk. This vulnerability demonstrates the importance of proper resource cleanup in system utilities and aligns with ATT&CK technique T1484.001, which covers the use of credential dumping and privilege escalation through system manipulation. Organizations should implement immediate mitigation strategies including patching to ncpfs version 2.2.7 or later, monitoring for the presence of lock files, and implementing automated cleanup procedures to prevent accumulation of stale lock files that could lead to system instability or service disruption.