CVE-2015-6937 in Solaris
Summary
by MITRE
The __rds_conn_create function in net/rds/connection.c in the Linux kernel through 4.2.3 allows local users to cause a denial of service (NULL pointer dereference and system crash) or possibly have unspecified other impact by using a socket that was not properly bound.
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Analysis
by VulDB Data Team • 05/29/2023
The vulnerability identified as CVE-2015-6937 resides within the Linux kernel's remote direct memory access rds subsystem, specifically in the __rds_conn_create function located in net/rds/connection.c. This flaw represents a critical security issue that affects Linux kernel versions through 4.2.3, demonstrating a classic null pointer dereference vulnerability that can be exploited by local attackers to disrupt system operations. The vulnerability stems from inadequate validation of socket binding states during connection creation processes, creating a pathway for malicious actors to manipulate kernel memory structures and potentially escalate their privileges or execute arbitrary code.
The technical implementation of this vulnerability occurs when a local user creates a socket that has not been properly bound to a network address, subsequently triggering the __rds_conn_create function without proper parameter validation. This function fails to verify that the socket state is valid before proceeding with connection establishment, leading to a scenario where a null pointer reference occurs during memory access operations. The underlying cause aligns with CWE-476, which describes null pointer dereference conditions that can result in system crashes and potential privilege escalation. When the kernel attempts to access memory locations pointed to by uninitialized or improperly configured socket structures, the system experiences a segmentation fault that manifests as a kernel panic or system crash, effectively creating a denial of service condition.
The operational impact of CVE-2015-6937 extends beyond simple system availability disruption, as it represents a potential privilege escalation vector that could allow local users to gain elevated system privileges. The vulnerability can be exploited through local user accounts without requiring network access or special permissions, making it particularly dangerous in multi-user environments where system integrity is paramount. Attackers can leverage this flaw to crash the kernel and potentially execute arbitrary code with kernel-level privileges, as documented in the ATT&CK framework under privilege escalation techniques. The denial of service aspect alone can be devastating in production environments where system uptime is critical, potentially causing service interruptions that affect business operations and data availability.
Mitigation strategies for CVE-2015-6937 primarily focus on kernel updates and system hardening measures. The most effective approach involves applying the official kernel patches released by the Linux kernel development team, which address the improper socket validation in the __rds_conn_create function. System administrators should prioritize updating to kernel versions 4.2.4 and later, where the vulnerability has been resolved through proper input validation and null pointer checks. Additionally, implementing kernel lockdown mechanisms and restricting local user privileges can reduce the attack surface, while monitoring for suspicious socket creation patterns can help detect potential exploitation attempts. The vulnerability highlights the importance of proper kernel memory management and input validation, emphasizing that even local privilege escalation vulnerabilities can have far-reaching consequences for system security and availability.