CVE-2017-0077 in Windows
Summary
by MITRE
The kernel-mode drivers in Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, Windows 10 Gold, 1511, 1607, 1703, and Windows Server 2016 allow a local authenticated attacker to execute a specially crafted application to obtain information, or in Windows 7 and later, cause denial of service, aka "Win32k Information Disclosure Vulnerability."
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Analysis
by VulDB Data Team • 12/22/2020
The CVE-2017-0077 vulnerability represents a critical information disclosure flaw within the Windows kernel-mode drivers that affects multiple operating system versions including Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, Windows 10 Gold, 1511, 1607, 1703, and Windows Server 2016. This vulnerability specifically resides in the win32k.sys driver component which manages user-mode graphics and windowing functionality, making it a prime target for privilege escalation attacks. The flaw allows a local authenticated attacker with standard user privileges to execute malicious applications that can either extract sensitive information from system memory or cause system instability leading to denial of service conditions.
The technical implementation of this vulnerability stems from improper validation of user-supplied data within the kernel-mode driver functions. When the win32k.sys driver processes certain graphics-related API calls, it fails to properly validate input parameters, creating opportunities for attackers to manipulate memory structures and extract information that should remain protected. This type of vulnerability falls under CWE-125, known as "Out-of-bounds Read," where the driver reads memory locations beyond the intended bounds, potentially exposing kernel memory contents including sensitive data, credentials, or system configuration details. The vulnerability's impact is amplified by the fact that it operates within kernel space, meaning any information disclosure can potentially expose system-level secrets that would normally be protected from user-mode access.
From an operational perspective, this vulnerability presents significant risks to enterprise environments where Windows systems are prevalent. The local authentication requirement means that attackers must first establish a foothold on a target system through legitimate user accounts, but once achieved, they can leverage this vulnerability to extract sensitive information or cause service disruptions that could impact business operations. The vulnerability's presence in Windows 7 and later versions makes it particularly concerning for organizations that have not fully transitioned to newer operating systems, as these systems remain in production environments and are often targeted by adversaries seeking to exploit known weaknesses. The potential for denial of service conditions means that attackers could destabilize systems and potentially cause cascading failures in critical infrastructure components that rely on stable Windows environments.
Security professionals should implement immediate mitigations including applying the relevant Microsoft security updates that address the win32k.sys driver vulnerability. The patching strategy should prioritize critical systems and those with high-value assets, as the vulnerability's exploitation can lead to information disclosure that may enable further attacks. Network segmentation and access controls should be enhanced to limit local user access where possible, while monitoring should be implemented to detect unusual patterns of API calls that might indicate exploitation attempts. Organizations should also consider implementing endpoint detection and response solutions that can identify suspicious behavior patterns associated with kernel-mode exploitation techniques. The vulnerability's classification under the ATT&CK framework as part of the privilege escalation tactics makes it particularly relevant for security teams to monitor for indicators of compromise related to kernel-level attacks, as such activities often precede more sophisticated breaches. Regular vulnerability assessments should include checking for the presence of unpatched systems running affected Windows versions, as the continued existence of vulnerable systems creates persistent attack vectors for adversaries seeking to establish persistent access to enterprise networks.