CVE-2018-6771 in Jiangmin
Summary
by MITRE
In Jiangmin Antivirus 16.0.0.100, the driver file (KrnlCall.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 0x99008224.
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Analysis
by VulDB Data Team • 01/02/2020
The vulnerability identified as CVE-2018-6771 affects Jiangmin Antivirus version 16.0.0.100 and represents a critical security flaw within the kernel-mode driver component known as KrnlCall.sys. This driver operates at the highest privilege level within the operating system, making it a prime target for exploitation and a significant concern for system stability and security. The vulnerability manifests through improper input validation mechanisms within the driver's handling of IOCTL (Input/Output Control) requests, specifically when processing the ioctl code 0x99008224. The lack of proper validation creates an opportunity for malicious actors to manipulate the driver's behavior through crafted input parameters, potentially leading to system-wide consequences that extend far beyond simple service disruption.
The technical nature of this flaw places it firmly within the category of improper input validation issues, which are classified under CWE-20 by the Common Weakness Enumeration catalog. This weakness occurs when a program does not properly validate or sanitize input data before processing it, leading to unexpected behavior that can be exploited by attackers. The vulnerability specifically impacts the driver's ability to handle user-mode requests sent through the Windows kernel interface, where the ioctl 0x99008224 serves as a communication channel between the antivirus service and the kernel driver. When local users submit malformed or unexpected input values to this ioctl handler, the driver fails to validate these inputs properly, creating a potential pathway for exploitation that could result in system crashes or more severe consequences.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as demonstrated by the potential for unspecified other impacts mentioned in the original description. Local users who can execute code on the target system can leverage this vulnerability to trigger blue screen of death (BSOD) conditions, effectively rendering the system unusable until a reboot occurs. However, the unspecified nature of other potential impacts suggests that this vulnerability may provide a foundation for more sophisticated attacks, potentially including privilege escalation or system compromise. The fact that this affects a kernel-mode driver means that successful exploitation could potentially allow attackers to bypass traditional security controls and gain deeper system access. The local nature of the vulnerability does not diminish its severity, as local attackers often have the ability to establish persistent access or combine this vulnerability with other exploits to achieve more significant objectives.
Mitigation strategies for CVE-2018-6771 should focus on both immediate remediation and long-term security improvements. The most effective immediate solution involves updating to a patched version of Jiangmin Antivirus that addresses the input validation deficiencies in the KrnlCall.sys driver. System administrators should also implement additional security measures including kernel-mode driver protection, application whitelisting, and monitoring for suspicious driver activity. From a defensive perspective, this vulnerability aligns with ATT&CK technique T1068 which covers 'Exploitation for Privilege Escalation', and T1059 which covers 'Command and Scripting Interpreter'. Organizations should also consider implementing runtime application protection and kernel debugging mechanisms to detect and prevent exploitation attempts. The vulnerability underscores the importance of proper input validation in kernel-mode components and highlights the need for comprehensive security testing of driver code, particularly in antivirus and security software where kernel-level access is required for functionality.