CVE-2020-1885 in Oculus
Summary
by MITRE
Writing to an unprivileged file from a privileged OVRRedir.exe process in Oculus Desktop before 1.44.0.32849 on Windows allows local users to write to arbitrary files and consequently gain privileges via vectors involving a hard link to a log file.
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Analysis
by VulDB Data Team • 10/09/2020
The vulnerability identified as CVE-2020-1885 resides within the Oculus Desktop software ecosystem on Windows platforms, specifically affecting versions prior to 1.44.0.32849. This flaw represents a critical privilege escalation vulnerability that leverages a design weakness in how the OVRRedir.exe process handles file operations, creating a pathway for local attackers to execute arbitrary code with elevated privileges. The vulnerability stems from improper privilege separation between the privileged OVRRedir.exe process and unprivileged user file operations, creating a dangerous attack surface that can be exploited through symbolic link manipulation.
The technical implementation of this vulnerability involves the OVRRedir.exe process running with elevated privileges while interacting with log files that can be manipulated by unprivileged users through hard link attacks. When the privileged process attempts to write to what it believes is a legitimate log file, an attacker can create a hard link to a target file of their choice, causing the privileged process to write data to the attacker-controlled location instead of the intended log file. This type of vulnerability falls under the CWE-276 category of insecure file permissions and improper privilege management, where a process with elevated privileges operates on files that should remain protected from unauthorized modification. The flaw demonstrates a classic improper privilege separation issue where the system fails to properly validate file access paths and does not adequately enforce access controls during file operations.
The operational impact of CVE-2020-1885 is severe and far-reaching, as it enables local privilege escalation attacks that can result in complete system compromise. An attacker with low-privilege user access can leverage this vulnerability to write arbitrary data to system-critical files, potentially leading to the installation of malicious software, modification of system binaries, or creation of persistent backdoors. This vulnerability specifically impacts the Oculus Desktop environment and affects users running affected versions of the software, making it particularly concerning for gaming and virtual reality environments where users may have elevated privileges for software installation and configuration. The attack requires local access and the ability to create hard links, but once exploited, it provides a persistent means of elevation that can be difficult to detect and remediate.
Mitigation strategies for CVE-2020-1885 should focus on immediate software updates to version 1.44.0.32849 or later, which includes patches addressing the privilege escalation vector through improved file access controls and hard link validation. Organizations should implement strict access control policies that limit file creation and modification capabilities for privileged processes, particularly when dealing with log files and temporary storage locations. The solution involves ensuring that privileged processes validate file paths and do not follow symbolic or hard links to arbitrary locations during write operations. Additionally, system administrators should monitor for unauthorized hard link creation and implement security controls that prevent unprivileged users from manipulating file system structures that could be exploited by privileged processes. This vulnerability aligns with ATT&CK technique T1068 which covers local privilege escalation through improper file permissions and access controls, making it a critical target for security hardening efforts. The fix implemented by Oculus addresses the root cause by ensuring that the OVRRedir.exe process properly validates file access and prevents the exploitation of hard link-based privilege escalation attacks.