CVE-2014-9491 in illumos
Summary
by MITRE
The devzvol_readdir function in illumos does not check the return value of a strchr call, which allows remote attackers to cause a denial of service (NULL pointer dereference and panic) via unspecified vectors.
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Analysis
by VulDB Data Team • 12/16/2024
The vulnerability identified as CVE-2014-9491 resides within the devzvol_readdir function of the illumos operating system kernel, representing a critical flaw that can be exploited to trigger system instability and denial of service conditions. This issue specifically affects the ZFS (Zettabyte File System) implementation within illumos, which is a Unix-like operating system derived from Solaris. The vulnerability manifests when the system processes directory read operations on virtual device volumes, creating a scenario where remote attackers can manipulate system behavior through unspecified vectors that lead to kernel-level crashes.
The technical root cause of this vulnerability lies in improper error handling within the devzvol_readdir function, which fails to validate the return value of a strchr function call. The strchr function searches for a specific character within a string and returns a pointer to the first occurrence of that character or NULL if not found. In this case, the absence of validation means that when strchr returns NULL due to a missing character match, the subsequent code attempts to dereference this NULL pointer without proper checks. This fundamental flaw in defensive programming creates a path where malicious input can directly lead to kernel panic conditions, as the system attempts to access memory at a null address. The vulnerability is classified as a NULL pointer dereference, which is a well-documented pattern that can result in system crashes and is categorized under CWE-476.
From an operational perspective, this vulnerability presents a significant risk to systems running illumos-based environments, particularly those exposed to untrusted network traffic or remote management interfaces. The remote exploitability means that attackers do not need local access to cause system disruptions, making it particularly dangerous in enterprise environments where such systems may be exposed to external networks. The denial of service impact extends beyond simple service interruption, as kernel panics can result in complete system crashes, requiring manual intervention and potentially causing data loss or extended downtime. This vulnerability affects the stability of ZFS storage systems, which are critical components in enterprise storage infrastructure, potentially impacting database servers, file servers, and other mission-critical applications that rely on ZFS for data management.
The exploitation of this vulnerability aligns with techniques described in the ATT&CK framework under the T1499 category for network denial of service, where adversaries target system stability through kernel-level manipulation. The lack of proper input validation and error checking demonstrates a failure in the principle of least privilege and defensive programming practices that should be fundamental to kernel development. Organizations running illumos systems should prioritize immediate patching to address this vulnerability, as the window of opportunity for exploitation remains open. The fix typically involves adding proper validation checks after the strchr call to ensure that NULL return values are handled gracefully rather than allowing the system to proceed with null pointer dereference operations. Additionally, system administrators should implement monitoring for unusual system behavior that might indicate exploitation attempts, particularly around ZFS-related operations and directory traversal activities that could trigger the vulnerable code path.