CVE-2011-3408 in Windows
Summary
by MITRE
Csrsrv.dll in the Client/Server Run-time Subsystem (aka CSRSS) in the Win32 subsystem in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2, R2, and R2 SP1, and Windows 7 Gold and SP1 does not properly check permissions for sending inter-process device-event messages from low-integrity processes to high-integrity processes, which allows local users to gain privileges via a crafted application, aka "CSRSS Local Privilege Elevation Vulnerability."
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Analysis
by VulDB Data Team • 03/20/2021
The CVE-2011-3408 vulnerability represents a critical privilege escalation flaw within the Windows operating system's Client/Server Run-time Subsystem component. This vulnerability specifically targets the csrsrv.dll module which operates as a core element of the Win32 subsystem responsible for managing process creation and termination operations. The flaw resides in the improper validation of permissions when processing inter-process device-event messages, creating a pathway for malicious exploitation that directly undermines the operating system's security model. The vulnerability affects multiple Windows versions including Windows xp sp2 and sp3, windows server 2003 sp2, windows vista sp2, windows server 2008 sp2 and r2, and windows 7 gold and sp1, making it particularly widespread across the windows ecosystem. This issue manifests as a local privilege escalation vulnerability where low-integrity processes can manipulate high-integrity processes through crafted device-event messages, effectively bypassing the operating system's mandatory integrity control mechanisms.
The technical implementation of this vulnerability stems from the failure of the CSRSS subsystem to properly validate the integrity levels of processes sending device-event messages. When low-integrity processes attempt to communicate with high-integrity processes through the csrsrv.dll component, the system fails to enforce proper access controls that should prevent such cross-integrity boundary violations. This flaw allows malicious applications running at lower integrity levels to craft specific device-event messages that can be processed by high-integrity processes, potentially enabling privilege escalation attacks. The vulnerability specifically relates to how the system handles inter-process communication between processes operating at different integrity levels, where the expected security boundaries are not properly enforced. This weakness is categorized under the common weakness enumeration as a privilege escalation vulnerability and aligns with attack techniques described in the mitre att&ck framework under privilege escalation tactics, particularly focusing on process injection and integrity level manipulation methods.
The operational impact of CVE-2011-3408 is severe and potentially devastating for affected systems. Local attackers who successfully exploit this vulnerability can elevate their privileges from standard user level to system level, effectively gaining complete control over the compromised machine. This privilege escalation capability enables attackers to perform actions such as installing malicious software, modifying system files, accessing sensitive data, and creating persistent backdoors. The vulnerability is particularly dangerous because it requires minimal user interaction and can be exploited by malicious applications that are already running on the system, making detection and prevention challenging. The attack vector involves crafting a specially designed application that leverages the improper permission checking in csrsrv.dll to send malicious device-event messages to high-integrity processes, which then execute with elevated privileges. This type of attack can be particularly effective in enterprise environments where users may have standard accounts but the system is configured with elevated privileges for administrative tasks.
Mitigation strategies for CVE-2011-3408 should focus on both immediate remediation and long-term security hardening measures. Microsoft released security updates that address this vulnerability through proper permission validation in the CSRSS subsystem, and system administrators should ensure all affected systems are patched with the latest security updates. Additionally, implementing application whitelisting policies can prevent malicious applications from executing on systems, while enabling mandatory integrity control enforcement helps maintain proper process isolation. System administrators should also consider implementing additional security controls such as disabling unnecessary services, hardening the operating system configuration, and monitoring for unusual process behavior that might indicate exploitation attempts. The vulnerability's classification as a privilege escalation issue aligns with standard security best practices that emphasize the principle of least privilege and proper access control enforcement. Organizations should also consider implementing endpoint detection and response solutions to monitor for potential exploitation attempts and maintain comprehensive security logging to facilitate forensic analysis in case of successful attacks.