CVE-2018-7273 in Linux
Summary
by MITRE
In the Linux kernel through 4.15.4, the floppy driver reveals the addresses of kernel functions and global variables using printk calls within the function show_floppy in drivers/block/floppy.c. An attacker can read this information from dmesg and use the addresses to find the locations of kernel code and data and bypass kernel security protections such as KASLR.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 12/07/2024
The vulnerability identified as CVE-2018-7273 represents a critical information disclosure flaw within the Linux kernel's floppy driver implementation. This issue affects kernel versions through 4.15.4 and stems from improper handling of debugging information within the show_floppy function located in drivers/block/floppy.c. The vulnerability manifests when the floppy driver's debugging routines execute printk calls that inadvertently expose kernel memory addresses to unauthorized users. These addresses correspond to kernel functions and global variables, creating a significant security risk that can be exploited by malicious actors to bypass essential kernel security mechanisms.
The technical flaw resides in the show_floppy function's implementation which utilizes printk statements to display kernel memory addresses during floppy drive operations. When a floppy drive is accessed or probed, the kernel's floppy driver routine executes code that prints debugging information containing the actual memory addresses of kernel functions and data structures. This information becomes accessible through the kernel's dmesg buffer, which can be read by unprivileged users or processes. The exposure of these memory addresses directly undermines the kernel's security architecture by providing attackers with crucial information needed for advanced exploitation techniques.
The operational impact of this vulnerability extends beyond simple information disclosure, as it fundamentally weakens kernel security protections that are designed to prevent exploitation. The most significant consequence involves bypassing Kernel Address Space Layout Randomization KASLR which is a critical defense mechanism against kernel exploits. When attackers can obtain kernel memory addresses through dmesg output, they gain the ability to construct more sophisticated attacks that would otherwise be impossible to mount successfully. This vulnerability particularly affects systems running kernel versions up to 4.15.4 where the debugging output remains unfiltered and accessible to userspace applications. The exposure of kernel function addresses enables attackers to develop exploits that can directly target specific kernel code locations, making exploitation significantly more reliable and effective.
The security implications of CVE-2018-7273 align with CWE-200 which describes improper exposure of sensitive information, and can be categorized under ATT&CK technique T1068 for "Exploitation for Privilege Escalation." The vulnerability's exploitation requires minimal privileges since dmesg output is accessible to unprivileged users, making it particularly dangerous in multi-user environments. Systems administrators should consider this issue as part of their broader security posture assessment, especially when implementing kernel security hardening measures. The flaw demonstrates how seemingly benign debugging code can create substantial security vulnerabilities, highlighting the importance of careful code review and security testing of kernel modules. Organizations should prioritize patching affected systems and implementing proper kernel security configurations to prevent unauthorized access to kernel memory addresses through kernel log buffers.
Mitigation strategies for this vulnerability include applying the relevant kernel security patches that address the information disclosure in the floppy driver's show_floppy function. System administrators should also implement proper access controls on kernel log buffers and consider disabling unnecessary kernel debugging features on production systems. The vulnerability serves as a reminder of the importance of maintaining up-to-date kernel versions and implementing comprehensive kernel security hardening practices that can prevent similar information disclosure issues from compromising system security. Regular security audits of kernel modules and debugging output should be conducted to identify and remediate similar vulnerabilities before they can be exploited by malicious actors.