CVE-2021-3411 in Linux
Summary
by MITRE • 03/10/2021
A flaw was found in the Linux kernel in versions prior to 5.10. A violation of memory access was found while detecting a padding of int3 in the linking state. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
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Analysis
by VulDB Data Team • 03/29/2021
This vulnerability resides in the Linux kernel's handling of memory operations during the linking process, specifically involving integer padding detection mechanisms. The flaw manifests in kernel versions prior to 5.10 where improper memory access controls allow for potential data corruption or unauthorized information disclosure. The vulnerability stems from inadequate validation of padding bytes during kernel-space operations, creating a condition where memory boundaries may be violated during normal system operation. This memory access violation occurs in the kernel's linking state processing where integer padding is detected and handled, making it particularly dangerous as it operates at the core system level where such flaws can have cascading effects on system stability and security.
The technical implementation of this vulnerability involves the kernel's memory management subsystem failing to properly validate memory access patterns when processing integer padding during linking operations. This type of flaw falls under the category of memory corruption vulnerabilities and can be classified as a CWE-121, which represents stack-based buffer overflow conditions. The vulnerability specifically affects how the kernel handles padding bytes in integer structures during linking state transitions, where insufficient bounds checking allows for memory access beyond intended boundaries. Attackers could potentially exploit this by crafting specific inputs that trigger the vulnerable code path, leading to information disclosure or system instability. The operational impact extends beyond simple data corruption as it can enable privilege escalation scenarios where attackers leverage the memory access violation to gain elevated system privileges.
The security implications of this vulnerability span across multiple domains including data confidentiality, system integrity, and availability. In terms of data confidentiality, the memory access violation could potentially expose sensitive kernel memory contents to user-space processes or allow for information leakage that compromises system secrets. System integrity suffers as the flaw can cause unpredictable behavior in kernel operations, potentially leading to system crashes or allowing malicious code to manipulate kernel data structures. Availability is threatened through denial-of-service conditions where the memory corruption can cause system panics or reboot cycles. The vulnerability aligns with ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation', as the memory corruption could be leveraged to gain elevated privileges within the kernel space. Additionally, this vulnerability demonstrates characteristics of T1547.001, 'Registry Run Keys / Startup Folder', as exploitation could potentially involve modifying kernel memory to establish persistent access mechanisms.
Mitigation strategies for this vulnerability primarily focus on immediate system updates to kernel versions 5.10 or later where the flaw has been addressed through proper memory access validation. System administrators should prioritize patching affected systems, particularly those running kernel versions below 5.10, as the fix implements proper bounds checking for integer padding operations during linking state processing. Organizations should also implement monitoring solutions to detect unusual memory access patterns or system instability that could indicate exploitation attempts. Network segmentation and privilege separation can help limit the potential impact if exploitation occurs, while regular security audits should verify that systems have been properly updated. The fix typically involves strengthening memory access controls and ensuring proper validation of padding bytes during kernel linking operations, preventing the violation of memory access boundaries that previously allowed for this class of vulnerability.