CVE-2017-15116 in Linux
Summary
by MITRE
The rngapi_reset function in crypto/rng.c in the Linux kernel before 4.2 allows attackers to cause a denial of service (NULL pointer dereference).
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Analysis
by VulDB Data Team • 01/16/2023
The vulnerability identified as CVE-2017-15116 represents a critical null pointer dereference flaw within the Linux kernel's random number generation subsystem. This issue exists in the rngapi_reset function located in the crypto/rng.c file and affects kernel versions prior to 4.2. The vulnerability arises from improper input validation and error handling within the random number generator API, creating a scenario where malicious actors can exploit the function to trigger system instability.
The technical exploitation of this vulnerability occurs when an attacker manipulates the random number generator interface in a way that causes the rngapi_reset function to attempt dereferencing a null pointer. This type of flaw falls under CWE-476, which specifically addresses null pointer dereference conditions that can lead to system crashes or denial of service attacks. The vulnerability demonstrates a classic improper validation issue where the function fails to properly check for null references before attempting to access memory locations, leading to kernel panic conditions that completely disrupt system operations.
From an operational perspective, this vulnerability presents a significant risk for systems relying on consistent random number generation for cryptographic operations, security protocols, and system stability. The denial of service impact means that any system running an affected kernel version could be rendered unavailable through a simple attack vector that requires minimal privileges. This makes the vulnerability particularly dangerous in environments where system availability is critical, such as enterprise servers, cloud infrastructure, or security-sensitive applications that depend on reliable random number generation for key material creation and cryptographic operations.
The attack surface for this vulnerability extends to any application or service that interfaces with the Linux kernel's random number generator API, including but not limited to cryptographic services, network security protocols, and system utilities that require secure random number generation. According to ATT&CK framework category T1499, this vulnerability represents a denial of service technique that can be leveraged to disrupt system availability. The exploitation process typically involves crafting specific input parameters to the random number generator interface that trigger the null pointer dereference condition, resulting in system crashes that require manual intervention to recover.
Mitigation strategies for CVE-2017-15116 primarily focus on kernel version updates to 4.2 or later, which contain the necessary patches to address the null pointer dereference condition. System administrators should prioritize updating their kernel versions across all affected systems, particularly those running in production environments where availability is paramount. Additionally, implementing proper input validation at the application level when interacting with kernel random number generation interfaces can provide an additional layer of protection. The vulnerability highlights the importance of maintaining current kernel versions and following security best practices for system hardening, as the fix implemented in kernel version 4.2 properly validates pointer references before attempting memory access operations. Organizations should also consider implementing monitoring solutions that can detect unusual system behavior patterns that may indicate exploitation attempts, providing early warning capabilities for potential attacks targeting this specific vulnerability.