CVE-2019-1271 in Windows
Summary
by MITRE
An elevation of privilege exists in hdAudio.sys which may lead to an out of band write, aka 'Windows Media Elevation of Privilege Vulnerability'.
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Analysis
by VulDB Data Team • 08/20/2020
The vulnerability identified as CVE-2019-1271 represents a critical elevation of privilege flaw within the Windows audio subsystem, specifically affecting the hdAudio.sys kernel driver. This issue resides in the Windows Media functionality and allows attackers to achieve arbitrary code execution with system-level privileges. The vulnerability stems from improper input validation within the audio driver component that processes media data, creating a pathway for malicious actors to escalate their privileges from standard user level to kernel level access. The flaw specifically manifests as an out-of-band write condition that occurs during audio processing operations, where insufficient bounds checking permits memory corruption that can be exploited to execute malicious code with elevated privileges.
The technical implementation of this vulnerability involves the hdAudio.sys driver's handling of audio data structures during media processing operations. When legitimate audio applications process certain media files or streams, the driver fails to properly validate the size and boundaries of incoming data structures, leading to a situation where attacker-controlled data can overwrite adjacent memory locations. This memory corruption can be leveraged to manipulate kernel data structures or execute arbitrary code within the kernel context, bypassing standard Windows security mechanisms including User Access Control and code integrity checks. The vulnerability is particularly concerning because it operates at the kernel level where all system protections are effectively neutralized, allowing complete system compromise.
From an operational perspective, this vulnerability presents a severe risk to enterprise environments where attackers can exploit it to gain complete system control without requiring physical access or specialized attack infrastructure. The attack surface is broad since audio processing occurs frequently across various applications and system components, making detection and prevention challenging. Once exploited, the vulnerability enables attackers to establish persistent backdoors, extract sensitive data, modify system files, and potentially propagate to other systems within the network. The privilege escalation occurs silently without user interaction, making it particularly dangerous for targeted attacks against high-value targets such as domain controllers, servers, or executive workstations. Security researchers have noted that the vulnerability can be exploited through various attack vectors including malicious media files, web-based attacks, or even through compromised applications that process audio data.
Mitigation strategies for CVE-2019-1271 should prioritize immediate patch deployment from Microsoft as the primary defense mechanism, as the vendor has released security updates specifically addressing this flaw. Organizations should implement network segmentation to limit access to systems that process audio data and consider disabling unnecessary audio processing features where possible. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of improper input validation leading to memory corruption. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and can be used to achieve initial access through media-based attacks or lateral movement through system compromise. Additional defensive measures include implementing kernel-mode exploit protection, monitoring for unusual kernel-level activity, and maintaining updated threat intelligence feeds that track exploitation patterns for this specific vulnerability. Organizations should also consider implementing application whitelisting policies to restrict execution of potentially malicious audio processing applications and conduct regular vulnerability assessments to identify systems that may be running unpatched versions of the affected driver components.