CVE-2010-3861 in Linux
Summary
by MITRE
The ethtool_get_rxnfc function in net/core/ethtool.c in the Linux kernel before 2.6.36 does not initialize a certain block of heap memory, which allows local users to obtain potentially sensitive information via an ETHTOOL_GRXCLSRLALL ethtool command with a large info.rule_cnt value, a different vulnerability than CVE-2010-2478.
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Analysis
by VulDB Data Team • 10/06/2021
The vulnerability described in CVE-2010-3861 represents a classic information disclosure flaw within the Linux kernel's network subsystem, specifically affecting the ethtool utility functionality. This issue resides in the ethtool_get_rxnfc function located in net/core/ethtool.c, which handles reception filter configuration operations for network interfaces. The flaw manifests when processing ETHTOOL_GRXCLSRLALL commands, which are designed to retrieve reception filter rules from network hardware. The vulnerability becomes exploitable when a local user submits an ethtool command with a large info.rule_cnt value, creating a scenario where the kernel fails to properly initialize memory before using it.
The technical root cause of this vulnerability stems from improper memory initialization practices within the kernel's network management code. When the ethtool_get_rxnfc function processes a request with an oversized rule count parameter, it allocates memory to store the filter rule information but neglects to initialize the allocated heap memory block. This uninitialized memory contains residual data from previous operations, potentially including sensitive information such as kernel stack contents, memory addresses, or other confidential data that was previously stored in those memory locations. The vulnerability is classified as a memory exposure issue under CWE-119, specifically involving uninitialized memory access that can lead to information leakage.
From an operational perspective, this vulnerability poses significant risks to system security as it allows local users to potentially extract sensitive information from kernel memory spaces. The attack vector requires local system access, making it a privilege escalation concern rather than a remote exploit, but it can still be leveraged by malicious users with low-privilege accounts to gain insights into the kernel's internal state. The extracted information could potentially aid in further exploitation attempts, including kernel address space layout randomization (ASLR) bypasses or other advanced attack techniques. This vulnerability is categorized under the attack pattern of information disclosure as outlined in the ATT&CK framework, specifically targeting the T1005 technique for data from local system.
The impact of this vulnerability extends beyond simple information disclosure, as the leaked memory contents could contain critical system information that might be used to plan more sophisticated attacks. The memory exposure could reveal kernel memory layouts, stack contents, or other sensitive data that would normally be protected from user-space access. This makes the vulnerability particularly concerning for systems where kernel memory integrity is paramount. The flaw was addressed in kernel versions 2.6.36 and later, where proper memory initialization practices were implemented to ensure that all allocated memory blocks are properly cleared before use. Organizations should ensure their systems are updated to patched kernel versions to mitigate this risk, as the vulnerability represents a fundamental security flaw in memory management practices that could potentially be exploited in combination with other vulnerabilities to achieve more severe outcomes.