CVE-2019-6492 in Smart Defrag
Summary
by MITRE
SmartDefragDriver.sys (2.0) in IObit Smart Defrag 6 never frees an executable kernel pool that is allocated with user defined bytes and size when IOCTL 0x9C401CC4 is called. This kernel pointer can be leaked if the kernel pool becomes a "big" pool.
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Analysis
by VulDB Data Team • 08/04/2023
The vulnerability identified as CVE-2019-6492 resides within the SmartDefragDriver.sys kernel driver component of IObit Smart Defrag 6 version 2.0, representing a critical memory management flaw that directly impacts system stability and security. This issue manifests through improper handling of kernel pool memory allocation and deallocation mechanisms, specifically when the driver processes IOCTL (Input/Output Control) requests with the specific identifier 0x9C401CC4. The driver's failure to properly free executable kernel pool memory creates a persistent memory leak that can accumulate over time, leading to system performance degradation and potential exploitation opportunities. The vulnerability is particularly concerning because it involves kernel-level memory management where improper handling can compromise the entire operating system's integrity.
The technical flaw stems from the driver's inability to properly manage memory allocation within the kernel pool, specifically when processing user-defined bytes and size parameters through the IOCTL interface. When IOCTL 0x9C401CC4 is invoked, the driver allocates memory from the kernel pool but fails to release it subsequently, creating a memory leak that persists throughout the system's operational lifecycle. This leak becomes particularly problematic when the kernel pool transitions to "big" pool allocation states, as the leaked memory pointers can be exposed through various kernel memory access mechanisms. The vulnerability falls under CWE-401: Improper Release of Memory Before Removing Last Reference, which specifically addresses memory management issues where resources are not properly deallocated, creating both performance and security implications. The executable nature of the leaked kernel pool memory means that attackers could potentially leverage this memory for code execution or information disclosure attacks.
The operational impact of this vulnerability extends beyond simple memory consumption issues to encompass broader system stability and security concerns. The persistent memory leak can lead to system slowdowns, application crashes, and eventually system instability as kernel memory becomes exhausted. More critically, the leaked kernel pointers provide potential attack vectors for privilege escalation attacks, as adversaries could potentially manipulate or predict memory locations to gain elevated system privileges. This vulnerability aligns with ATT&CK technique T1068: Exploitation for Privilege Escalation, where memory corruption vulnerabilities are exploited to gain higher privileges within the system. Additionally, the issue could be leveraged in conjunction with other kernel exploits to create more sophisticated attack scenarios, making it a significant concern for enterprise environments where system stability and security are paramount.
Mitigation strategies for CVE-2019-6492 should focus on immediate driver updates and system hardening measures to prevent exploitation. The primary recommendation involves updating to the latest version of IObit Smart Defrag software where the memory management issues have been addressed through proper kernel pool deallocation mechanisms. System administrators should also implement monitoring solutions to detect unusual memory consumption patterns that might indicate exploitation attempts. Kernel patching and memory protection mechanisms such as Kernel Address Space Layout Randomization (KASLR) and Control Flow Guard (CFG) can provide additional defense-in-depth measures. Organizations should also consider implementing driver signature enforcement and restricting execution of unsigned kernel drivers to minimize the risk of exploitation. The vulnerability highlights the importance of proper kernel memory management practices and underscores the necessity of thorough security testing for kernel-mode drivers to prevent similar issues in other software components.