CVE-2018-6524 in AVS
Summary
by MITRE
In nProtect AVS V4.0 4.0.0.38, the driver file (TKFsAv.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 0x220c20.
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Analysis
by VulDB Data Team • 01/01/2020
The vulnerability identified as CVE-2018-6524 affects nProtect AVS V4.0 version 4.0.0.38 and represents a critical security flaw within the kernel-mode driver component of the antivirus software. This issue resides in the TKFsAv.SYS driver file which serves as the core system component responsible for low-level system operations and protection functions. The vulnerability stems from insufficient input validation mechanisms within the driver's handling of IOCTL (Input/Output Control) commands, specifically the command with code 0x220c20. This particular IOCTL interface provides a communication channel between user-mode applications and the kernel-mode driver, enabling privileged system operations. The lack of proper validation of input parameters creates an exploitable condition that can be leveraged by local attackers to manipulate the driver's behavior.
The technical flaw manifests when the driver processes IOCTL 0x220c20 without adequate verification of the data structures or parameter values provided by the calling application. This validation gap allows an attacker to submit malformed or unexpected input values that can cause the driver to behave unpredictably. When the driver encounters these unvalidated inputs, it can lead to memory corruption issues, invalid memory access patterns, or other internal state inconsistencies that ultimately result in system instability. The most immediate and observable impact is the generation of a Blue Screen of Death (BSOD) which occurs when the Windows kernel detects critical system errors that cannot be recovered from. The vulnerability's potential for unspecified other impacts suggests that beyond the immediate denial of service condition, there may be additional security implications including privilege escalation opportunities or further system compromise possibilities.
From an operational perspective, this vulnerability presents a significant risk to systems running the affected nProtect AVS version as it allows local users to trigger system crashes that can disrupt normal operations and potentially provide a foothold for further attacks. The local nature of the vulnerability means that any user with access to the system can potentially exploit it, making it particularly dangerous in multi-user environments or when the antivirus software is installed with elevated privileges. The impact extends beyond simple system downtime as the BSOD conditions can cause data loss, application instability, and may provide attackers with information about the system's internal state. This vulnerability directly relates to CWE-129 Input Validation and CWE-787 Out-of-bounds Write, both of which are fundamental security weaknesses that can lead to system compromise. The ATT&CK framework categorizes this issue under T1068 Valid Accounts and T1490 Inhibit System Recovery, as local privilege escalation and denial of service capabilities can be leveraged to maintain persistent access or disrupt system availability.
Mitigation strategies for CVE-2018-6524 should prioritize immediate patching of the nProtect AVS software to the latest version that addresses the input validation issues in the TKFsAv.SYS driver. System administrators should implement strict access controls and user privilege management to limit the potential for exploitation, particularly in environments where local access cannot be fully trusted. Network segmentation and monitoring solutions should be deployed to detect unusual system crash patterns or BSOD occurrences that may indicate exploitation attempts. Additionally, regular security assessments should include verification of driver integrity and proper input validation mechanisms within security software components. Organizations should also consider implementing endpoint detection and response solutions that can identify abnormal driver behavior patterns and provide real-time alerts when suspicious IOCTL operations occur. The vulnerability underscores the importance of proper kernel-mode driver security practices and highlights the need for comprehensive input validation at all levels of system software to prevent exploitation of similar issues in other security products.