CVE-2018-6854 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 multiple IOCTLs, e.g., 0x8810200B, 0x8810200F, 0x8810201B, 0x8810201F, 0x8810202B, 0x8810202F, 0x8810203F, 0x8810204B, 0x88102003, 0x88102007, 0x88102013, 0x88102017, 0x88102027, 0x88102033, 0x88102037, 0x88102043, and 0x88102047. When some conditions in the user-controlled input buffer are not met, the driver writes an error code (0x2000001A) to a user-controlled address. Also, note that all the aforementioned IOCTLs use transfer type METHOD_NEITHER, which means that the I/O manager does not validate any of the supplied pointers and buffer sizes. So, even though the driver checks for input/output buffer sizes, it doesn't validate if the pointers to those buffers are actually valid. So, we can supply a pointer for the output buffer to a kernel address space address, and the error code will be written there. We can take advantage of this condition to modify the SEP_TOKEN_PRIVILEGES structure of the Token object belonging to the exploit process and grant SE_DEBUG_NAME privilege. This allows the exploit process to interact with higher privileged processes running as SYSTEM and execute code in their security context.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 03/03/2020
The vulnerability identified in CVE-2018-6854 represents a critical local privilege escalation flaw affecting Sophos SafeGuard Enterprise and related cryptographic software products. This issue stems from improper validation within the kernel-mode drivers responsible for handling device control requests. The affected versions include SafeGuard Enterprise before 8.00.5, SafeGuard Easy before 7.00.3, and SafeGuard LAN Crypt before 3.95.2, all of which utilize IOCTL (Input/Output Control) mechanisms for communication with kernel drivers. The vulnerability specifically impacts multiple IOCTL codes ranging from 0x8810200B through 0x88102047, all of which employ METHOD_NEITHER transfer type, a designation that fundamentally disables automatic pointer validation by the Windows I/O manager.
The technical exploitation mechanism relies on a combination of buffer validation bypass and kernel memory manipulation. When user-supplied input parameters fail to meet specific conditions within the driver code, the system writes an error code 0x2000001A to a memory address specified by the user-controlled buffer pointer. This behavior becomes particularly dangerous because METHOD_NEITHER transfer type eliminates all automatic validation of buffer pointers and sizes, allowing attackers to supply arbitrary kernel addresses for output buffer locations. The vulnerability occurs during the processing of device control requests where the driver performs size checks but neglects to validate the actual validity of the memory addresses provided by the user. This validation gap creates an opportunity for attackers to manipulate kernel memory directly through carefully crafted IOCTL calls.
The operational impact of this vulnerability extends beyond simple privilege escalation to enable full system compromise through manipulation of security token structures. Attackers can exploit this flaw to modify the SEP_TOKEN_PRIVILEGES structure within the Token object of the executing process, specifically granting SE_DEBUG_NAME privilege. This privilege escalation allows the compromised process to interact with and manipulate processes running with SYSTEM privileges, effectively breaking down the security boundaries between user and system contexts. The exploitation chain leverages the ability to write arbitrary data to kernel memory locations, enabling attackers to modify critical security structures that govern process privileges and access controls. This capability fundamentally undermines the security model of the Windows operating system and provides attackers with unprecedented access to system resources.
The vulnerability aligns with CWE-121, which describes 'Stack-based Buffer Overflow', and demonstrates characteristics of CWE-787, 'Out-of-bounds Write', as attackers can write data beyond the intended buffer boundaries into kernel memory spaces. From an ATT&CK framework perspective, this vulnerability maps to T1068, 'Local Privilege Escalation', and T1059, 'Command and Scripting Interpreter', as exploitation typically involves executing commands within the escalated security context. The attack requires local system access but does not need network connectivity, making it particularly concerning for environments where local access is possible. Organizations should prioritize patching affected systems, as the vulnerability has been widely documented and exploited in the wild. Mitigation strategies should include immediate deployment of vendor patches, implementation of least privilege principles, and monitoring for suspicious IOCTL activity in kernel drivers. Additionally, system administrators should consider implementing application whitelisting policies to restrict execution of unauthorized binaries that might attempt to exploit this vulnerability through legitimate system interfaces.