CVE-2015-2042 in Linux
Summary
by MITRE
net/rds/sysctl.c in the Linux kernel before 3.19 uses an incorrect data type in a sysctl table, which allows local users to obtain potentially sensitive information from kernel memory or possibly have unspecified other impact by accessing a sysctl entry.
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Analysis
by VulDB Data Team • 03/10/2022
The vulnerability identified as CVE-2015-2042 resides within the Linux kernel's implementation of the Reliable Datagram Sockets (RDS) protocol subsystem, specifically in the net/rds/sysctl.c file. This flaw represents a classic information disclosure vulnerability that arises from improper data type handling within kernel sysctl tables. The issue affects Linux kernel versions prior to 3.19, making it a significant concern for systems running older kernel versions where patching may not have been applied. The vulnerability stems from the incorrect use of data types in sysctl table entries, which creates a mismatch between how data is stored and how it is accessed, potentially exposing kernel memory contents to local users who can manipulate these interfaces.
The technical exploitation of this vulnerability occurs through the manipulation of sysctl entries that are part of the RDS protocol implementation. When a sysctl table entry is configured with an incorrect data type, the kernel's sysctl subsystem may interpret memory contents incorrectly during read operations. This misinterpretation can lead to information disclosure scenarios where local attackers can access uninitialized kernel memory, kernel data structures, or other sensitive information that should remain protected within kernel space. The vulnerability's impact extends beyond simple information disclosure, as the improper data type handling could potentially enable more sophisticated attacks depending on the specific memory layout and the nature of the exposed data. The flaw aligns with CWE-128, which describes "Unsigned to Signed Conversion Error" and CWE-200, which covers "Information Exposure," demonstrating how improper data handling can create multiple attack vectors.
From an operational perspective, this vulnerability poses a significant risk to systems running affected kernel versions as local users can leverage it to gain access to potentially sensitive kernel information. The attack requires local system access but does not need elevated privileges, making it particularly concerning for multi-tenant environments or systems where privilege separation is not strictly enforced. The exposure of kernel memory can reveal information about system internals, memory layout, and potentially sensitive data structures that could be used in more advanced exploitation techniques. The unspecified other impacts mentioned in the vulnerability description suggest that beyond information disclosure, the improper data handling could potentially allow for more complex attacks such as privilege escalation or system stability compromise, though the exact nature of these additional impacts would depend on the specific memory contents that are exposed.
The mitigation strategy for CVE-2015-2042 involves applying the appropriate kernel security patches that correct the data type handling in the sysctl table entries within the RDS subsystem. System administrators should prioritize updating to Linux kernel version 3.19 or later where this vulnerability has been addressed through proper data type specification in the sysctl table implementation. Additionally, organizations should implement monitoring for any unusual sysctl access patterns that might indicate exploitation attempts. The fix typically involves correcting the data type definitions in the kernel source code to ensure that sysctl entries properly align with the actual data they contain, preventing the misinterpretation of kernel memory. This vulnerability demonstrates the importance of rigorous code review and testing for kernel subsystems, particularly those that expose interfaces to user space through sysctl mechanisms, and aligns with ATT&CK technique T1059.003 for system binary execution and T1068 for exploit for privilege escalation. Organizations should also consider implementing least privilege principles and limiting local user access to system interfaces where possible, though the vulnerability's nature as a local information disclosure means that access control measures alone cannot fully prevent exploitation.