CVE-2009-4005 in Linux
Summary
by MITRE
The collect_rx_frame function in drivers/isdn/hisax/hfc_usb.c in the Linux kernel before 2.6.32-rc7 allows attackers to have an unspecified impact via a crafted HDLC packet that arrives over ISDN and triggers a buffer under-read.
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Analysis
by VulDB Data Team • 08/28/2021
The vulnerability identified as CVE-2009-4005 resides within the Linux kernel's ISDN subsystem, specifically in the collect_rx_frame function located in drivers/isdn/hisax/hfc_usb.c. This flaw affects kernel versions prior to 2.6.32-rc7 and represents a critical buffer under-read condition that can be exploited through crafted HDLC packets transmitted over ISDN connections. The vulnerability occurs when the kernel processes incoming ISDN frames, creating a scenario where insufficient input validation allows maliciously constructed data to trigger memory access violations. The impact of this vulnerability extends beyond simple denial of service, as it can potentially enable arbitrary code execution or information disclosure depending on the exploitation context.
The technical nature of this vulnerability aligns with CWE-129, which addresses insufficient input validation, and more specifically relates to CWE-125, describing out-of-bounds read conditions. The flaw manifests when the collect_rx_frame function fails to properly validate the length of incoming HDLC frames before attempting to process them, resulting in a buffer under-read that can access memory locations outside the intended buffer boundaries. This type of vulnerability is particularly dangerous in kernel space contexts where memory corruption can lead to privilege escalation or system compromise. The attack vector involves sending specially crafted HDLC packets over ISDN connections, which are then processed by the vulnerable kernel driver without adequate bounds checking, creating an opportunity for attackers to manipulate memory contents or execute malicious code with kernel privileges.
The operational impact of CVE-2009-4005 represents a significant security risk for systems running vulnerable Linux kernel versions, particularly those utilizing ISDN hardware interfaces. Systems that rely on ISDN connections for telecommunications or network services become vulnerable to remote exploitation, potentially allowing attackers to gain unauthorized access to system resources or disrupt service availability. The vulnerability's exploitation can result in system crashes, data corruption, or more severe consequences such as privilege escalation to root level access. Organizations using affected kernel versions face potential compromise of their network infrastructure, especially in environments where ISDN interfaces are actively used for communication purposes. The vulnerability affects the broader Linux ecosystem and requires immediate attention from system administrators to prevent potential exploitation by malicious actors.
Mitigation strategies for CVE-2009-4005 primarily focus on kernel version updates, with the most effective solution being the upgrade to Linux kernel 2.6.32-rc7 or later versions where the vulnerability has been addressed through proper input validation and buffer boundary checking. System administrators should implement immediate patch management procedures to ensure all affected systems receive the necessary kernel updates. Additional defensive measures include network segmentation to isolate ISDN interfaces, implementing firewall rules to restrict ISDN traffic, and monitoring for unusual patterns in ISDN communications that might indicate exploitation attempts. The vulnerability also highlights the importance of secure coding practices in kernel development, particularly around input validation and memory management, which aligns with ATT&CK technique T1068, covering local privilege escalation through kernel vulnerabilities. Organizations should also consider implementing intrusion detection systems to monitor for exploitation attempts and maintain comprehensive backup and recovery procedures to address potential system compromise scenarios.