CVE-2018-5220 in K7
Summary
by MITRE
In K7 Antivirus 15.1.0306, the driver file (K7Sentry.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 0x95002610.
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Analysis
by VulDB Data Team • 12/19/2019
The vulnerability identified as CVE-2018-5220 resides within K7 Antivirus version 15.1.0306 and specifically targets the kernel-mode driver component known as K7Sentry.sys. This driver operates at the highest privilege level within the Windows operating system, making it a critical component that requires stringent security controls. 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 0x95002610. The absence of adequate validation allows malicious or malformed input data to be passed directly to kernel memory operations without proper sanitization or bounds checking.
The technical implementation of this vulnerability stems from the driver's failure to validate user-supplied parameters before executing potentially dangerous operations within kernel space. When a local user submits crafted input data through the vulnerable IOCTL interface, the driver processes this data without sufficient verification mechanisms. This lack of input validation creates an opportunity for privilege escalation and system instability. According to CWE classification, this represents a weakness in input validation (CWE-20) combined with improper handling of kernel-mode operations. The vulnerability allows for arbitrary code execution within kernel space, which can result in complete system compromise and is categorized under the ATT&CK technique T1068 for "Exploitation for Privilege Escalation."
The operational impact of CVE-2018-5220 extends beyond simple denial of service conditions, as local attackers can potentially achieve system crashes resulting in Blue Screen of Death (BSOD) scenarios. However, the vulnerability's true danger lies in its potential for more severe consequences including privilege escalation to SYSTEM level access, which would allow attackers to bypass all operating system security controls. The kernel-mode execution context means that any successful exploitation could result in complete system compromise, data theft, or persistent backdoor installation. The vulnerability affects all systems running the vulnerable K7 Antivirus version, regardless of the underlying Windows architecture, and presents a significant risk to enterprise environments where antivirus software is deployed. Organizations should consider the ATT&CK technique T1059 for "Command and Scripting Interpreter" as a potential follow-up action once privilege escalation is achieved through this vulnerability.
Mitigation strategies for CVE-2018-5220 should focus on immediate remediation through official vendor patches or updates. System administrators must ensure that all K7 Antivirus installations are updated to versions that address this vulnerability, as the vendor likely released a security patch to correct the input validation issues. Additionally, implementing application whitelisting policies and restricting local user privileges can help limit the attack surface. The principle of least privilege should be enforced, particularly for antivirus driver components that operate with elevated permissions. Monitoring for unusual kernel-mode activity and implementing proper input validation controls within the antivirus driver architecture are recommended defensive measures. Organizations should also consider the ATT&CK technique T1562 for "Impair Defenses" as a potential indicator of exploitation attempts, including monitoring for driver loading anomalies or unexpected system behavior. Regular security assessments and vulnerability scanning should be conducted to identify similar issues in other security software components that may present similar kernel-mode exploitation opportunities.