CVE-2012-4398 in Linux
Summary
by MITRE
The __request_module function in kernel/kmod.c in the Linux kernel before 3.4 does not set a certain killable attribute, which allows local users to cause a denial of service (memory consumption) via a crafted application.
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Analysis
by VulDB Data Team • 12/29/2021
The vulnerability identified as CVE-2012-4398 resides within the Linux kernel's module loading mechanism, specifically in the __request_module function located in kernel/kmod.c. This flaw represents a significant security weakness that affects Linux kernel versions prior to 3.4, where the function fails to properly configure a critical killable attribute during module request processing. The absence of this attribute creates an exploitable condition that can be leveraged by malicious actors to consume excessive system resources.
The technical implementation of this vulnerability stems from the kernel's handling of module loading requests through the __request_module function. When a user-space application requests a kernel module, this function is invoked to facilitate the loading process. However, due to the missing killable attribute setting, the kernel process responsible for module loading can become unresponsive or enter a state where it cannot be properly terminated. This condition allows an attacker to repeatedly trigger module loading requests without proper resource cleanup, leading to progressive memory consumption and system instability.
From an operational perspective, this vulnerability presents a severe denial of service threat that can compromise system availability and performance. Local users with minimal privileges can exploit this weakness to exhaust system memory resources, potentially causing system crashes, application failures, or complete system unresponsiveness. The impact extends beyond simple resource exhaustion as the vulnerability can be used to create persistent system instability that affects critical services and applications running on the affected system. The vulnerability's local nature means that exploitation requires only user-level access, making it particularly dangerous as it can be leveraged by malicious insiders or compromised accounts.
The vulnerability maps to CWE-400, which specifically addresses "Uncontrolled Resource Consumption" in software systems. This classification accurately describes the memory consumption aspect of the vulnerability where system resources are consumed without proper bounds or cleanup mechanisms. Additionally, the vulnerability aligns with ATT&CK technique T1499.004, which covers "Endpoint Denial of Service" through resource exhaustion, demonstrating how this flaw can be weaponized for system disruption attacks. The lack of proper killable attribute handling creates a process management weakness that allows for unbounded resource consumption.
Mitigation strategies for this vulnerability primarily focus on kernel version updates, as the issue was resolved in Linux kernel version 3.4 and subsequent releases. System administrators should prioritize updating to patched kernel versions to eliminate the vulnerability. Organizations can also implement monitoring solutions to detect unusual memory consumption patterns that might indicate exploitation attempts. Process monitoring tools can help identify when kernel module loading processes are consuming excessive resources or failing to terminate properly. Additionally, implementing proper access controls and privilege management can limit the potential impact of local exploitation attempts, though the vulnerability's nature makes complete prevention difficult without kernel-level fixes. The remediation process requires careful consideration of system compatibility and testing to ensure that kernel updates do not introduce regressions in system functionality or application compatibility.