CVE-2010-2960 in Linux
Summary
by MITRE
The keyctl_session_to_parent function in security/keys/keyctl.c in the Linux kernel 2.6.35.4 and earlier expects that a certain parent session keyring exists, which allows local users to cause a denial of service (NULL pointer dereference and system crash) or possibly have unspecified other impact via a KEYCTL_SESSION_TO_PARENT argument to the keyctl function.
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Analysis
by VulDB Data Team • 11/30/2024
The vulnerability identified as CVE-2010-2960 resides within the Linux kernel's key management subsystem, specifically in the keyctl_session_to_parent function located in security/keys/keyctl.c. This flaw represents a critical security issue affecting Linux kernel versions up to and including 2.6.35.4, where the kernel fails to properly validate the existence of a required parent session keyring before attempting to reference it. The vulnerability manifests when a local attacker invokes the keyctl system call with the KEYCTL_SESSION_TO_PARENT argument, creating a scenario where the kernel's key management logic encounters a NULL pointer dereference. This particular flaw falls under the CWE-476 category of NULL Pointer Dereference, which is a common vulnerability pattern where software attempts to access a memory location pointed to by a null reference. The impact of this vulnerability extends beyond simple denial of service, as the improper handling of kernel memory structures could potentially lead to more severe consequences including system instability or arbitrary code execution depending on the specific conditions under which the vulnerability is exploited.
The technical implementation of this vulnerability exploits the kernel's insufficient input validation mechanisms within the keyctl system call interface. When a user-space application invokes keyctl with the KEYCTL_SESSION_TO_PARENT command, the kernel's key management code path assumes the existence of a parent session keyring without first verifying its presence in the current keyring context. This assumption leads to a critical failure in the kernel's memory management subsystem where a NULL pointer is dereferenced during the session keyring transfer operation. The vulnerability demonstrates a classic case of inadequate error handling in kernel space operations, where the absence of proper validation checks creates a path for malicious or accidental exploitation. The flaw is particularly concerning because it operates entirely within the kernel's privileged execution context, meaning that local users who can execute keyctl commands can potentially trigger this vulnerability. From an operational perspective, this vulnerability represents a significant risk to system stability as the NULL pointer dereference results in immediate system crashes or kernel panics, effectively rendering the affected system unavailable to legitimate users. The exploitability of this vulnerability is relatively straightforward since it only requires local user access to execute the keyctl command with the specific argument, making it a particularly dangerous issue for systems where untrusted users might have shell access.
The operational impact of CVE-2010-2960 extends beyond immediate system crashes to encompass broader security implications within kernel space. When the kernel experiences a NULL pointer dereference in the keyctl_session_to_parent function, it typically results in a kernel oops or system panic, causing the entire system to become unresponsive and requiring manual intervention for recovery. This denial of service condition can be particularly damaging in production environments where system availability is critical for business operations. The vulnerability's potential for unspecified other impacts suggests that under certain conditions, attackers might be able to leverage this flaw for more sophisticated attacks beyond simple system crashes. The ATT&CK framework categorizes this type of vulnerability under privilege escalation and denial of service techniques, where attackers can manipulate kernel-level functions to compromise system integrity. Organizations running affected kernel versions face significant risk as this vulnerability can be exploited to disrupt services, potentially allowing attackers to gain further access to system resources or cause prolonged outages that can impact business continuity. The vulnerability also highlights the importance of proper input validation and error handling in kernel space code, as the lack of validation for critical kernel data structures creates opportunities for exploitation that could be amplified by other vulnerabilities in the system. Security researchers have noted that such kernel-level NULL pointer dereferences often serve as entry points for more complex attack chains, where the initial denial of service can be used to facilitate further exploitation attempts or to create conditions that allow for privilege escalation. The remediation of this vulnerability requires kernel updates to versions that properly validate the existence of parent session keyrings before attempting to reference them, emphasizing the critical importance of keeping kernel versions current with security patches.