CVE-2018-6852 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 0x80202298. By crafting an input buffer we can control the execution path to the point where the nt!memset function is called to zero out contents of 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 described in CVE-2018-6852 represents a critical local privilege escalation flaw affecting Sophos SafeGuard Enterprise and related cryptographic software products. This vulnerability resides in the kernel-mode drivers of the affected software versions, specifically within the handling of IOCTL (Input/Output Control) operations. The issue manifests when processing IOCTL 0x80202298, which allows unprivileged users to manipulate memory structures in ways that should only be accessible to privileged processes. The flaw stems from inadequate input validation and memory management within the driver's kernel code, creating a path where user-supplied data can influence the execution flow of critical system functions.
The technical exploitation of this vulnerability hinges on the manipulation of memory through controlled input buffers that ultimately lead to the invocation of nt!memset function. This function, when called with user-controlled parameters, enables attackers to overwrite memory locations containing critical security metadata. The vulnerability specifically targets the object header structure of privileged processes, where the security descriptor pointer resides. By carefully crafting the input buffer, an attacker can cause the memset operation to zero out the security descriptor pointer or modify the security descriptor itself, effectively undermining the access control mechanisms that protect privileged processes. This memory corruption directly enables privilege escalation to SYSTEM level execution context, as the compromised security descriptors no longer properly enforce access controls.
The operational impact of CVE-2018-6852 extends beyond simple privilege escalation, as it provides attackers with the capability to execute arbitrary code within the highest privilege level of the operating system. This vulnerability is particularly dangerous because it requires no special privileges to exploit, making it accessible to any local user with basic system access. The attack vector is relatively straightforward, involving the creation of a malicious input buffer and subsequent execution of the vulnerable IOCTL command. Once successful, the exploit allows attackers to bypass all standard security mechanisms, potentially enabling full system compromise, data exfiltration, or establishment of persistent backdoors. The vulnerability affects multiple versions of Sophos security products, creating widespread exposure across enterprise environments that rely on these cryptographic solutions for data protection.
Mitigation strategies for CVE-2018-6852 primarily involve immediate patching of affected Sophos SafeGuard products to versions 8.00.5, 7.00.3, and 3.95.2 respectively, which contain the necessary fixes to address the memory handling flaws. Organizations should also implement additional security measures including restricting local user access to systems running affected software, monitoring for suspicious IOCTL activity, and ensuring proper access controls are in place. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and may also relate to CWE-787, concerning out-of-bounds write operations. From an ATT&CK perspective, this vulnerability maps to privilege escalation techniques and specifically to T1068, which covers the exploitation of legitimate credentials and system privileges, enabling attackers to achieve SYSTEM-level access through kernel-mode exploitation. Network administrators should also consider implementing endpoint detection and response solutions to identify potential exploitation attempts and monitor for unusual memory manipulation patterns that may indicate exploitation of this vulnerability.