CVE-2007-3850 in Linux
Summary
by MITRE
The eHCA driver in Linux kernel 2.6 before 2.6.22, when running on PowerPC, does not properly map userspace resources, which allows local users to read portions of physical address space.
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Analysis
by VulDB Data Team • 07/29/2019
The eHCA driver vulnerability identified as CVE-2007-3850 represents a critical privilege escalation flaw within the Linux kernel's PowerPC architecture support. This vulnerability specifically affects kernel versions prior to 2.6.22 and stems from improper memory mapping mechanisms that fail to adequately validate userspace resource access. The flaw exists in the eHCA (enhanced Host Channel Adapter) driver implementation which handles communication with certain IBM PowerPC hardware components, creating a pathway for local attackers to bypass kernel memory protection boundaries.
The technical root cause of this vulnerability lies in the driver's inadequate handling of memory mapping operations between userspace and kernel space contexts. When the eHCA driver processes requests from userspace applications, it fails to properly validate or constrain the physical address ranges that can be accessed through the mapped memory regions. This improper validation creates a direct mapping vulnerability where userspace processes can potentially access arbitrary physical memory addresses within the system's address space. The vulnerability manifests as a classic kernel memory disclosure issue that allows unauthorized read access to physical memory locations that should remain protected from userspace access.
From an operational perspective, this vulnerability enables local users to read portions of physical address space that contain sensitive information including kernel memory structures, cryptographic keys, and potentially confidential data from other processes. The impact extends beyond simple information disclosure as it can facilitate further exploitation techniques such as kernel address space layout randomization (ASLR) bypasses, heap spraying attacks, or even direct kernel memory manipulation. Attackers could leverage this privilege escalation vector to gain elevated privileges and potentially compromise the entire system. The vulnerability is particularly concerning in multi-user environments where local access could be gained through various attack vectors including compromised user accounts or shared system resources.
The vulnerability aligns with CWE-125: Out-of-bounds Read and CWE-787: Out-of-bounds Write categories, representing memory safety issues that can lead to unauthorized information disclosure and privilege escalation. From an ATT&CK framework perspective, this vulnerability maps to T1068: Exploitation for Privilege Escalation and T1005: Data from Local System, enabling adversaries to gain higher privileges and extract sensitive data from the target system. Mitigation strategies should focus on immediate kernel upgrades to version 2.6.22 or later where the memory mapping validation has been corrected. Additionally, system administrators should implement proper access controls and monitoring to detect anomalous memory access patterns, while also considering kernel hardening techniques such as kernel page table isolation and memory protection mechanisms. Organizations should also conduct thorough vulnerability assessments to identify systems running affected kernel versions and implement comprehensive patch management procedures to ensure all systems remain protected against this and similar memory mapping vulnerabilities.