CVE-2007-0773 in Enterprise Linux Desktop
Summary
by MITRE
The Linux kernel before 2.6.9-42.0.8 in Red Hat 4.4 allows local users to cause a denial of service (kernel OOPS from null dereference) via fput in a 32-bit ioctl on 64-bit x86 systems, an incomplete fix of CVE-2005-3044.1.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 07/20/2021
The vulnerability described in CVE-2007-0773 represents a critical denial of service flaw within the Linux kernel that specifically affects systems running Red Hat Enterprise Linux 4.4 with kernel versions prior to 2.6.9-42.0.8. This issue demonstrates the complex nature of kernel-level vulnerabilities that can arise from incomplete security fixes, creating a dangerous precedent where remediation efforts inadvertently leave systems exposed to new attack vectors. The vulnerability manifests through a specific interaction between 32-bit ioctl operations and 64-bit x86 architecture, highlighting the intricate challenges of maintaining compatibility across different system architectures while ensuring security.
The technical flaw stems from an insufficient fix for CVE-2005-3044, which was itself a denial of service vulnerability. In this case, the fput function within the kernel's file handling subsystem contains a null pointer dereference condition that occurs during ioctl operations on 64-bit x86 systems when executed in a 32-bit compatibility mode. This creates a scenario where a local malicious user can trigger a kernel panic or OOPS condition by carefully crafting a specific ioctl call that causes the kernel to attempt to dereference a null pointer in the file descriptor cleanup process. The vulnerability is particularly dangerous because it operates at the kernel level, meaning that successful exploitation can bring down the entire system or cause unpredictable behavior that may be difficult to recover from without manual intervention.
The operational impact of this vulnerability extends beyond simple system availability concerns, as it represents a fundamental failure in the kernel's memory management and error handling mechanisms. When exploited, the vulnerability can cause the kernel to crash and generate an OOPS message, effectively rendering the system unusable until manual reboot or system recovery procedures are initiated. This type of denial of service attack is particularly concerning in enterprise environments where system uptime is critical, as it can be used to disrupt services without requiring elevated privileges or complex attack vectors. The vulnerability affects systems running on 64-bit x86 hardware but with 32-bit compatibility mode enabled, which was common in enterprise deployments during the time period when this vulnerability was prevalent.
From a cybersecurity perspective, this vulnerability aligns with several ATT&CK framework techniques including privilege escalation through kernel exploits and denial of service operations. The CWE classification for this issue would fall under CWE-476 which describes NULL Pointer Dereference, with additional considerations for CWE-119 which addresses memory corruption issues. The vulnerability demonstrates how incomplete security patches can create new attack surfaces, a common pattern in cybersecurity where remediation efforts that don't fully address root causes leave systems exposed to similar or related threats. Organizations affected by this vulnerability should prioritize immediate patching, as the fix requires updating to the specific kernel version 2.6.9-42.0.8 or later to properly address the null pointer dereference in the fput function. The remediation process should include thorough testing in development environments before deployment to production systems to ensure that the updated kernel does not introduce compatibility issues with existing applications or system configurations.