CVE-2013-6832 in FreeBSD
Summary
by MITRE
The nand_ioctl function in sys/dev/nand/nand_geom.c in the nand driver in the kernel in FreeBSD 10 and earlier does not properly initialize a certain data structure, which allows local users to obtain sensitive information from kernel memory via a crafted ioctl call.
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Analysis
by VulDB Data Team • 05/15/2018
The vulnerability identified as CVE-2013-6832 resides within the FreeBSD kernel's NAND flash driver implementation, specifically in the nand_ioctl function located in sys/dev/nand/nand_geom.c. This flaw represents a classic case of improper initialization of kernel data structures that can lead to information disclosure. The vulnerability affects FreeBSD versions 10 and earlier, indicating it was present in a significant portion of the operating system's kernel codebase during that timeframe. The issue manifests when the nand_ioctl function fails to properly initialize a critical data structure before processing ioctl commands, creating a potential attack vector for local malicious actors.
The technical implementation of this vulnerability stems from the failure to properly initialize memory structures within the kernel space. When a crafted ioctl call is made to the NAND driver, the uninitialized data structure contains remnants of previous kernel memory contents that were not explicitly cleared or overwritten. This improper initialization creates a scenario where sensitive information, potentially including kernel memory addresses, credential data, or other confidential information, can be leaked to the calling process. The vulnerability operates at the kernel level, making it particularly dangerous as it bypasses normal user-space memory protection mechanisms and directly accesses kernel memory space.
From an operational impact perspective, this vulnerability enables local users to perform information disclosure attacks against the FreeBSD system. An attacker with local access can exploit this weakness to extract sensitive kernel memory contents that may contain system configuration details, memory layout information, or other potentially useful data for further exploitation. The attack vector requires local system access, which means it cannot be exploited remotely, but it still represents a significant security risk in environments where local access is possible or where privilege escalation attacks are being considered. This type of vulnerability can be particularly useful in advanced exploitation scenarios where attackers need to gather system information to plan more sophisticated attacks.
The vulnerability aligns with CWE-457, which describes "Use of Uninitialized Variable" in software development practices, and it can be mapped to ATT&CK technique T1059.001 for command and scripting interpreter execution. The attack pattern follows a typical information gathering phase where an adversary attempts to extract system information from kernel memory to better understand the target environment. The remediation strategy involves proper initialization of all kernel data structures before they are used, ensuring that no sensitive information leaks from previous operations or memory contents. FreeBSD addressed this vulnerability through patch updates that properly initialize the affected data structure, requiring system administrators to apply these updates to maintain system security. The fix demonstrates the importance of proper kernel memory management practices and highlights the critical need for thorough testing of kernel code to prevent such information disclosure vulnerabilities from being exploited by malicious actors.