CVE-2018-6853 in SafeGuard Enterprise
Summary
by MITRE
Sophos SafeGuard Enterprise before 8.00.5, SafeGuard Easy before 7.00.3, and SafeGuard LAN Crypt before 3.95.2 are vulnerable to Local Privilege Escalation via IOCTL 0x80206024. By crafting an input buffer we can control the execution path to the point where a global variable will be written to a user controlled address. We can take advantage of this condition to zero-out the pointer to the security descriptor in the object header of a privileged process or modify the security descriptor itself and run code in the context of a process running as SYSTEM.
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Analysis
by VulDB Data Team • 03/03/2020
The vulnerability identified as CVE-2018-6853 represents a critical local privilege escalation flaw affecting multiple Sophos SafeGuard products including SafeGuard Enterprise versions prior to 8.00.5, SafeGuard Easy versions before 7.00.3, and SafeGuard LAN Crypt versions before 3.95.2. This vulnerability resides in the kernel-mode drivers of these security products, specifically through an improperly validated IOCTL (Input/Output Control) command with the identifier 0x80206024. The flaw stems from inadequate input validation and buffer management within the driver's handling of user-supplied data, creating a condition where malicious input can manipulate the driver's execution flow and subsequently corrupt critical kernel memory structures.
The technical exploitation of this vulnerability involves crafting a specific input buffer that allows an attacker to control the execution path within the vulnerable driver. Through careful manipulation of the input data, an attacker can cause the driver to write to a global variable at a location controlled by the attacker's input. This memory corruption vulnerability operates at the kernel level where the driver maintains object headers containing security descriptors that govern access control permissions. The vulnerability is categorized under CWE-121 as a stack-based buffer overflow, though it manifests as a more complex memory corruption issue that enables arbitrary write primitives. The attack leverages the principle of privilege separation by targeting kernel-mode components that operate with elevated privileges, specifically those running in the SYSTEM context.
The operational impact of this vulnerability is severe as it allows any local user to escalate their privileges to SYSTEM level, effectively bypassing all operating system security controls. When exploited, the vulnerability enables attackers to zero out the pointer to the security descriptor within the object header or modify the security descriptor itself, thereby altering the access control permissions of privileged processes. This manipulation permits the execution of arbitrary code within the context of a process running with SYSTEM privileges, providing complete system compromise. The vulnerability affects systems where Sophos SafeGuard products are installed, potentially impacting enterprise environments where these security solutions are deployed for data encryption and protection. The attack requires local system access but does not necessitate network connectivity, making it particularly dangerous in environments where local privilege escalation is not typically restricted.
Mitigation strategies for CVE-2018-6853 primarily involve applying the vendor-provided patches and updates for the affected Sophos SafeGuard products. Organizations should immediately upgrade to the patched versions of SafeGuard Enterprise 8.00.5, SafeGuard Easy 7.00.3, and SafeGuard LAN Crypt 3.95.2 or later. Additionally, system administrators should implement principle of least privilege controls by restricting local user access to systems running these vulnerable components. Network segmentation and monitoring for suspicious IOCTL activity can help detect potential exploitation attempts. The vulnerability aligns with ATT&CK technique T1068 which describes local privilege escalation through kernel exploits, and T1059 which covers command and scripting interpreter usage. Security teams should also consider implementing behavioral monitoring solutions that can detect anomalous kernel-mode activity patterns consistent with this type of privilege escalation exploit, as the vulnerability operates at a level that bypasses traditional user-mode security controls and detection mechanisms.