CVE-2017-18550 in Linux
Summary
by MITRE
An issue was discovered in drivers/scsi/aacraid/commctrl.c in the Linux kernel before 4.13. There is potential exposure of kernel stack memory because aac_get_hba_info does not initialize the hbainfo structure.
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Analysis
by VulDB Data Team • 11/26/2023
The vulnerability identified as CVE-2017-18550 resides within the Linux kernel's aacraid driver component, specifically in the drivers/scsi/aacraid/commctrl.c file. This issue affects kernel versions prior to 4.13 and represents a classic case of information disclosure through improper memory initialization. The flaw manifests when the aac_get_hba_info function fails to properly initialize the hbainfo structure before populating it with data. This oversight creates a scenario where sensitive kernel stack memory contents may be inadvertently exposed to user-space applications through the driver interface.
The technical root cause of this vulnerability aligns with CWE-119, which addresses improper access to memory locations, and specifically relates to CWE-248, which deals with exposure of uninitialized memory. When the hbainfo structure is not initialized, portions of the kernel stack that contain previously allocated memory contents remain accessible. These uninitialized memory segments may contain sensitive data such as cryptographic keys, session tokens, or other confidential information that was previously stored in the same memory locations. The vulnerability operates at the kernel level, making it particularly dangerous as it can be exploited by malicious processes running with appropriate privileges or potentially even by unprivileged users in certain scenarios.
The operational impact of CVE-2017-18550 extends beyond simple information disclosure, as it can potentially enable more sophisticated attacks within the kernel space. Attackers could leverage this vulnerability to gather intelligence about the kernel's memory layout, potentially aiding in the development of more targeted exploits. The exposure occurs during the communication between the aacraid driver and user-space applications, where the driver's failure to initialize memory structures creates a pathway for sensitive kernel data to leak into user-accessible buffers. This type of vulnerability falls under the ATT&CK technique T1005, which involves data from local system storage, and could contribute to broader exploitation strategies involving kernel memory analysis and information gathering.
Mitigation strategies for CVE-2017-18550 primarily focus on upgrading to kernel versions 4.13 or later where the issue has been addressed through proper memory initialization practices. System administrators should prioritize patching affected systems, particularly those running older kernel versions that may be handling critical storage operations through aacraid controllers. Additionally, implementing proper access controls and monitoring for unusual memory access patterns can help detect potential exploitation attempts. The fix implemented in kernel 4.13 ensures that the hbainfo structure is properly initialized before data is copied into it, preventing the leakage of uninitialized kernel stack contents. Organizations should also consider implementing kernel hardening measures such as stack canaries and kernel address space layout randomization to further reduce the attack surface and potential impact of similar vulnerabilities.