CVE-2015-4004 in Linux
Summary
by MITRE
The OZWPAN driver in the Linux kernel through 4.0.5 relies on an untrusted length field during packet parsing, which allows remote attackers to obtain sensitive information from kernel memory or cause a denial of service (out-of-bounds read and system crash) via a crafted packet.
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Analysis
by VulDB Data Team • 05/20/2022
The vulnerability identified as CVE-2015-4004 resides within the OZWPAN driver component of the Linux kernel version 4.0.5 and earlier, representing a critical security flaw that undermines the integrity of kernel memory operations. This driver specifically handles wireless personal area network communications for certain USB devices, making it a potential attack vector for remote adversaries seeking to exploit kernel-level vulnerabilities. The flaw manifests through improper validation of packet length fields during the parsing process, creating a scenario where maliciously crafted packets can trigger unexpected behavior within the kernel's memory management subsystem.
The technical root cause of this vulnerability stems from the driver's reliance on untrusted data from incoming network packets without adequate bounds checking or validation mechanisms. When the OZWPAN driver processes incoming packets, it utilizes a length field provided by the remote attacker to determine how much data to read from the packet buffer. This unvalidated length field allows attackers to specify values that exceed the actual packet boundaries, resulting in out-of-bounds memory reads that can expose sensitive kernel memory contents to unauthorized access. The vulnerability classifies under CWE-129 as an improper input validation issue, specifically involving insufficient boundary checking during data processing operations.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable remote attackers to execute denial of service attacks that may crash the entire system. When the driver encounters a crafted packet with an oversized length field, the out-of-bounds read operations can cause kernel panics, system crashes, or unpredictable behavior that renders the affected system unusable. This type of vulnerability aligns with ATT&CK technique T1059.005, where adversaries leverage kernel-level exploits to achieve system compromise, and represents a significant threat to systems running vulnerable kernel versions. The memory exposure aspect of this vulnerability also falls under ATT&CK technique T1005, where adversaries collect data from the local system, potentially gaining access to sensitive kernel memory contents including cryptographic keys, credentials, or other confidential information.
Mitigation strategies for CVE-2015-4004 primarily involve upgrading to kernel versions 4.0.6 and later, where the vulnerability has been addressed through proper bounds checking and input validation mechanisms. System administrators should prioritize patching affected systems, particularly those running wireless network infrastructure or devices that utilize the OZWPAN driver. Additionally, network segmentation and firewall rules can be implemented to limit exposure to untrusted networks, though this approach provides only partial protection since the vulnerability can be exploited through various attack vectors. The fix implemented in newer kernel versions demonstrates proper defensive programming practices by validating all input data before processing, ensuring that length fields are checked against maximum allowable values and that buffer operations remain within safe boundaries. This vulnerability underscores the critical importance of robust input validation in kernel space operations and serves as a reminder of the potential catastrophic consequences when such validation is omitted or insufficiently implemented.