CVE-2012-5429 in VPN Client
Summary
by MITRE
The VPN driver in Cisco VPN Client on Windows does not properly interact with the kernel, which allows local users to cause a denial of service (kernel fault and system crash) via a crafted application, aka Bug ID CSCuc81669.
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Analysis
by VulDB Data Team • 12/21/2021
The vulnerability identified as CVE-2012-5429 represents a critical kernel interaction flaw within the Cisco VPN Client driver implementation on Windows operating systems. This issue stems from improper kernel handling mechanisms that allow local attackers to exploit weaknesses in the driver's memory management and system call processing. The vulnerability specifically affects the Windows VPN client component that interfaces directly with the kernel, creating a pathway for malicious applications to trigger system instability through crafted input sequences. The flaw manifests when the VPN driver fails to properly validate or handle certain kernel-level operations, leading to unpredictable behavior that can result in complete system failure.
The technical execution of this vulnerability involves exploiting the kernel interaction patterns within the Cisco VPN Client driver through carefully constructed applications that manipulate driver interfaces. When a local user executes a malicious application, the crafted input causes the driver to attempt invalid kernel operations or access unauthorized memory regions. This improper kernel interaction results in kernel faults that trigger system crashes and complete system instability. The vulnerability operates at a low system level where the driver's inability to properly handle kernel resources creates a condition that leads to kernel panics and system termination. The attack vector is particularly concerning because it requires only local user privileges, making it accessible to any user with access to the system.
The operational impact of CVE-2012-5429 extends beyond simple denial of service to potentially compromise entire system availability and stability. Organizations relying on Cisco VPN Client for remote access face significant risks when this vulnerability exists, as local users can effectively disable critical network connectivity and system functionality. The kernel-level nature of the flaw means that system administrators cannot easily recover from the resulting crashes without manual intervention or system restarts. This vulnerability directly impacts the availability component of the CIA triad and can be leveraged as part of broader attack strategies where initial access is achieved through other means. The flaw can also serve as a persistence mechanism or escalation vector in multi-stage attack scenarios where attackers first establish local presence before exploiting this kernel interaction weakness.
Mitigation strategies for CVE-2012-5429 should focus on immediate patch deployment and system hardening measures. Cisco released patches addressing this vulnerability through their security advisory process, and organizations must prioritize timely deployment of these updates to prevent exploitation. System administrators should also implement monitoring for suspicious driver behavior and kernel-level anomalies that may indicate exploitation attempts. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and can be mapped to ATT&CK technique T1059 for command and script interpreter usage. Additional protective measures include restricting local user privileges where possible, implementing application whitelisting policies, and conducting regular security assessments of VPN client implementations. Network segmentation and monitoring solutions should be deployed to detect unusual network activity that may indicate exploitation attempts, while regular system audits help identify potential compromise indicators associated with kernel-level vulnerabilities.