CVE-2012-1014 in Kerberos
Summary
by MITRE
The process_as_req function in the Key Distribution Center (KDC) in MIT Kerberos 5 (aka krb5) 1.10.x before 1.10.3 does not initialize a certain structure member, which allows remote attackers to cause a denial of service (uninitialized pointer dereference and daemon crash) or possibly execute arbitrary code via a malformed AS-REQ request.
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Analysis
by VulDB Data Team • 03/27/2021
The vulnerability identified as CVE-2012-1014 affects the Key Distribution Center implementation within MIT Kerberos 5 version 1.10.x prior to 1.10.3. This issue resides in the process_as_req function which handles Authentication Service requests within the Kerberos authentication protocol. The flaw manifests when the KDC processes malformed AS-REQ (Authentication Service Request) messages, creating a critical security gap that can be exploited by remote attackers to compromise system availability and potentially execute arbitrary code. The vulnerability represents a classic uninitialized memory access flaw that can lead to unpredictable behavior in the targeted service.
The technical root cause of this vulnerability stems from insufficient initialization of a structure member within the process_as_req function. When processing incoming AS-REQ requests, the KDC fails to properly initialize a specific pointer variable before using it in subsequent operations. This uninitialized pointer dereference creates a scenario where the daemon may attempt to access memory locations that contain arbitrary data from previous operations or stack contents. The vulnerability aligns with CWE-457: "Use of Uninitialized Variable" and represents a fundamental flaw in memory management practices within the Kerberos implementation. Attackers can craft malicious AS-REQ packets that trigger this uninitialized pointer usage, leading to either daemon crashes or more severe consequences including potential code execution.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable remote code execution in certain environments. When the KDC daemon encounters the malformed request, the uninitialized pointer dereference can cause immediate crashes and restart cycles, resulting in persistent availability issues for authentication services. However, under specific conditions where the uninitialized memory contents happen to contain valid code pointers or when exploitation techniques leverage the memory layout, attackers may achieve arbitrary code execution. This vulnerability affects organizations that rely heavily on Kerberos authentication, particularly those with centralized authentication infrastructure, as it can disrupt critical authentication services and potentially provide attackers with elevated privileges within the authenticated environment. The attack vector requires only network access to the KDC service, making it particularly dangerous for systems exposed to untrusted networks.
Mitigation strategies for CVE-2012-1014 primarily focus on immediate patch application to upgrade to MIT Kerberos 5 version 1.10.3 or later. Organizations should prioritize updating their Kerberos implementations across all systems hosting KDC services, including domain controllers, authentication servers, and any systems that depend on Kerberos for authentication. Network segmentation and access controls should be implemented to limit exposure of KDC services to only trusted networks and clients. Additionally, monitoring systems should be configured to detect unusual patterns in authentication request processing and potential crash events in KDC services. The vulnerability demonstrates the importance of proper memory initialization practices in security-critical code and serves as a reminder of the potential impact of seemingly simple initialization flaws in authentication systems. Security teams should also consider implementing intrusion detection systems capable of identifying malformed Kerberos AS-REQ requests and establishing incident response procedures for handling KDC service disruptions. This vulnerability aligns with ATT&CK technique T1078.002: "Valid Accounts: Kerberos" as it exploits weaknesses in the Kerberos authentication mechanism itself rather than bypassing authentication controls.