CVE-2018-6964 in Horizon Client
Summary
by MITRE
VMware Horizon Client for Linux (4.x before 4.8.0 and prior) contains a local privilege escalation vulnerability due to insecure usage of SUID binary. Successful exploitation of this issue may allow unprivileged users to escalate their privileges to root on a Linux machine where Horizon Client is installed.
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Analysis
by VulDB Data Team • 03/17/2023
The vulnerability identified as CVE-2018-6964 represents a critical local privilege escalation flaw within VMware Horizon Client for Linux installations. This issue affects versions 4.x prior to 4.8.0 and stems from the insecure handling of SUID (Set User ID) binaries within the client application's architecture. The flaw allows unprivileged local users to potentially elevate their privileges to the root level on systems where the vulnerable Horizon Client is installed, creating a significant security risk for enterprise environments that rely on VMware's virtual desktop infrastructure solutions.
The technical root cause of this vulnerability lies in the improper implementation of SUID permissions within the Horizon Client's binary components. SUID binaries are designed to execute with the permissions of the file owner rather than the user who invokes them, typically used for legitimate administrative functions. However, in this case, the vulnerable implementation fails to properly validate or restrict access to privileged operations, allowing malicious actors to exploit the elevated permissions. The vulnerability specifically manifests when the SUID binary does not adequately sanitize input parameters or enforce proper access controls, creating a pathway for privilege escalation through predictable or manipulable execution flows.
From an operational perspective, this vulnerability presents a substantial risk to organizations deploying VMware Horizon Client across their Linux infrastructure. Attackers who gain access to a low-privilege user account on a system running the vulnerable client can leverage this flaw to achieve root access, potentially compromising the entire system and any data or services running with elevated privileges. The impact extends beyond individual system compromise to include potential lateral movement within networks, as attackers could use the root access to establish persistent backdoors, exfiltrate sensitive information, or disrupt critical services. This vulnerability is particularly concerning in enterprise environments where Horizon Client is widely deployed for remote desktop access, as it could be exploited by both internal and external threat actors.
The vulnerability aligns with CWE-276, which addresses improper permissions for a resource, and maps to ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation'. Organizations should immediately implement mitigations including upgrading to VMware Horizon Client version 4.8.0 or later, which contains the necessary patches to address the SUID implementation issues. Additionally, system administrators should conduct thorough vulnerability assessments to identify all instances of the vulnerable software and ensure proper patch management protocols are in place. The remediation process should also include monitoring for suspicious privilege escalation attempts and implementing additional security controls such as mandatory access controls and privilege separation measures to limit the potential impact of such vulnerabilities in the event of exploitation.