CVE-2011-2011

Vulnerability

A use-after-free vulnerability exists in the win32k.sys kernel-mode driver component of Microsoft Windows. The flaw is triggered by incorrect driver object management when processing specially crafted input from user mode. This allows a local attacker to reference memory after it has been freed, leading to arbitrary code execution in kernel context. Affected versions include 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 [1].

Exploitation

To exploit this vulnerability, an attacker must have valid local logon credentials and the ability to execute a crafted application. The attacker runs the application, which leverages the use-after-free condition by manipulating kernel-mode driver object lifetimes. No user interaction beyond executing the malicious program is required; the attacker can be an unprivileged user [1].

Impact

Successful exploitation grants the attacker elevated privileges, allowing them to run arbitrary code in kernel mode. This results in complete compromise of the affected system: the attacker can install programs, view, change, or delete data, and create new accounts with full user rights [1].

Mitigation

Microsoft released security update MS11-077 on October 11, 2011, which addresses this vulnerability. Users should apply the update via Windows Update or by manually installing the patch. No workarounds are provided in the bulletin, but disabling automatic execution of font files on network shares may reduce the risk for related attack vectors [1].