CVE-2018-5081 in K7
Summary
by MITRE
In K7 AntiVirus 15.1.0306, the driver file (K7FWHlpr.sys) allows local users to cause a denial of service (BSOD) or possibly have unspecified other impact because of not validating input values from IOCtl 0x830020F0.
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Analysis
by VulDB Data Team • 12/19/2019
The vulnerability identified as CVE-2018-5081 resides within the K7 AntiVirus 15.1.0306 software suite, specifically targeting the kernel-mode driver component known as K7FWHlpr.sys. This driver operates at the highest privilege level within the Windows operating system, making it a critical component that requires rigorous security validation. The flaw manifests through improper input validation mechanisms within the driver's handling of IOCTL (Input/Output Control) requests, particularly when processing the specific control code 0x830020F0. This particular IOCTL interface serves as a communication channel between user-mode applications and the kernel-mode driver, enabling legitimate system operations while simultaneously creating potential attack vectors when input validation is insufficient.
The technical nature of this vulnerability stems from the driver's failure to validate input parameters received through the IOCTL 0x830020F0 request. When a local user submits malformed or unexpected input values to this interface, the driver processes these inputs without adequate sanitization or verification checks. This absence of input validation creates a condition where malicious or malformed data can cause the driver to behave unpredictably, leading to system instability and potential kernel-level crashes. The vulnerability specifically targets the Windows kernel's handling of device control requests, where insufficient bounds checking and parameter validation allows arbitrary data to be passed directly to kernel memory operations, bypassing normal security mechanisms that would typically prevent such unauthorized access patterns.
The operational impact of this vulnerability extends beyond simple denial of service conditions, potentially enabling more severe consequences including system crashes resulting in blue screen of death (BSOD) scenarios. Local users who exploit this vulnerability can force the system to become unstable and require rebooting, disrupting normal operations and potentially causing data loss if the system crashes during critical operations. The unspecified nature of additional potential impacts suggests that the vulnerability may provide opportunities for privilege escalation or other advanced exploitation techniques, though this remains unconfirmed. The fact that this affects a security product's kernel driver is particularly concerning as it could potentially be leveraged to bypass other security mechanisms or create persistent access points within the system.
This vulnerability aligns with CWE-129, Input Validation, and CWE-125, Out-of-bounds Read, as it demonstrates inadequate validation of input parameters and potential memory access violations. From an ATT&CK framework perspective, this vulnerability could be categorized under T1068, Exploitation for Privilege Escalation, and T1490, Inhibit System Recovery, when exploited to cause system instability or denial of service. The local privilege requirement means that exploitation is limited to users already authenticated on the system, but given that many security products run with elevated privileges, this could still represent a significant risk. Organizations should consider this vulnerability as part of their broader security posture assessment, particularly when evaluating endpoint protection solutions that operate at kernel level. Mitigation strategies should include immediate patching of the affected K7 AntiVirus software, implementing proper access controls to limit local user privileges, and monitoring for unusual system behavior that might indicate exploitation attempts.
The root cause of this vulnerability lies in the lack of proper input sanitization and validation within the kernel driver's IOCTL handling code. Modern secure coding practices would require comprehensive validation of all input parameters, including bounds checking, type verification, and proper error handling for malformed inputs. The vulnerability demonstrates the critical importance of applying defensive programming principles in kernel-mode code where errors can have system-wide consequences. Given that kernel drivers execute with the highest privilege level, any input validation failure can potentially lead to complete system compromise, making this class of vulnerability particularly dangerous. Security researchers and organizations should prioritize patch management for such vulnerabilities, as they represent common attack vectors that adversaries often target to establish persistent access or disrupt system operations.