CVE-2011-0030 in Windows
Summary
by MITRE
The Client/Server Run-time Subsystem (CSRSS) in Microsoft Windows XP SP2 and SP3 and Server 2003 SP2 does not properly kill processes after a logout, which allows local users to obtain sensitive information or gain privileges via a crafted application that continues to execute throughout the logout of one user and the login session of the next user, aka "CSRSS Elevation of Privilege Vulnerability," a different vulnerability than CVE-2010-0023.
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Analysis
by VulDB Data Team • 01/20/2025
The CSRSS elevation of privilege vulnerability represents a critical design flaw in Microsoft Windows operating systems that undermines fundamental security boundaries between user sessions. This vulnerability exists within the Client/Server Run-time Subsystem which is responsible for managing console sessions and process termination during user logouts. The flaw specifically manifests in Windows XP Service Pack 2 and 3, as well as Windows Server 2003 Service Pack 2, where the subsystem fails to properly terminate processes associated with the previous user session before allowing a new user to log in. This creates a window of opportunity where malicious applications can persist across session boundaries, effectively enabling privilege escalation attacks that bypass normal security controls. The vulnerability is particularly dangerous because it operates at the kernel level and exploits the inherent trust model between the operating system components and user applications, making it difficult to detect and prevent through standard security measures.
The technical implementation of this vulnerability stems from improper process management within the CSRSS component, which is categorized under CWE-264 as "Permissions, Privileges, and Access Controls." When a user logs out of a Windows system, the CSRSS should systematically terminate all processes associated with that user session and clean up all related resources before allowing the next user to establish their session. However, the flaw allows certain processes to continue executing with the privileges of the previous user, creating a persistent security risk. Attackers can craft malicious applications that leverage this behavior to execute code with elevated privileges, potentially gaining access to sensitive information or system resources that should be restricted to the original user context. The vulnerability operates through a specific sequence where the logout process completes but does not properly clean up all process handles, leaving them accessible to the subsequent login session. This behavior violates the principle of least privilege and creates an attack surface that can be exploited through various techniques including process injection and privilege escalation methods.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass broader security implications including information disclosure and potential system compromise. Local attackers can exploit this weakness to access sensitive data that was previously handled by the terminated processes, potentially including encryption keys, authentication tokens, or confidential user information. The vulnerability enables what cybersecurity professionals classify as a "session hijacking" attack pattern, which aligns with ATT&CK technique T1078.001 for Valid Accounts and T1078.002 for Additional Cloud Credentials. In practical attack scenarios, an attacker could use this vulnerability to maintain persistence across user sessions, monitor network traffic, or escalate privileges to system-level access. The impact is particularly severe in multi-user environments where administrators might assume that logout operations properly isolate user sessions. The vulnerability also affects the integrity of the operating system's security model by allowing processes to maintain state information across session boundaries, undermining the fundamental security assumptions that operating system designers rely upon for user isolation and privilege management.
Mitigation strategies for this vulnerability require both immediate patching and operational security enhancements. Microsoft released security updates that addressed the CSRSS process termination flaw, and organizations should ensure all affected systems are properly patched through standard update management procedures. The vulnerability highlights the importance of implementing comprehensive patch management programs and maintaining up-to-date security configurations. Additional defensive measures include monitoring for unusual process behavior during session transitions, implementing strict process monitoring tools, and configuring system policies that limit the ability of applications to persist across user sessions. Security professionals should also consider implementing network-based monitoring to detect potential exploitation attempts and establish baseline behavioral patterns for normal system operations. The vulnerability serves as a reminder of the critical importance of proper process lifecycle management in operating system security and demonstrates how seemingly minor implementation flaws in core system components can create significant security risks. Organizations should also review their security policies to ensure that user session management procedures account for these types of vulnerabilities and that appropriate access controls are maintained throughout the authentication and session management processes.