CVE-2022-49643 in Linux
Summary
by MITRE • 02/26/2025
In the Linux kernel, the following vulnerability has been resolved:
ima: Fix a potential integer overflow in ima_appraise_measurement
When the ima-modsig is enabled, the rc passed to evm_verifyxattr() may be negative, which may cause the integer overflow problem.
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Analysis
by VulDB Data Team • 06/12/2025
The vulnerability identified as CVE-2022-49643 represents a critical integer overflow condition within the Linux kernel's Integrity Measurement Architecture (IMA) subsystem. This flaw specifically affects the ima_appraise_measurement function when the ima-modsig feature is enabled, creating a potential vector for malicious exploitation that could compromise system integrity and security controls. The issue stems from improper handling of negative return codes from the evm_verifyxattr() function, which when passed through the measurement appraisal process, can trigger arithmetic overflow conditions that may lead to unpredictable system behavior.
The technical root cause of this vulnerability lies in the improper validation and handling of return codes within the IMA subsystem's measurement appraisal logic. When ima-modsig is enabled, the system performs extended verification operations that can return negative error codes indicating various failure conditions. However, the code fails to properly validate these negative values before they are processed in arithmetic operations, creating conditions where signed integer overflow can occur. This type of vulnerability maps directly to CWE-191, which specifically addresses integer underflow and overflow conditions, and represents a classic example of inadequate input validation in security-critical kernel code. The flaw demonstrates poor defensive programming practices where error codes are not properly sanitized before being used in subsequent calculations.
The operational impact of CVE-2022-49643 extends beyond simple system instability, potentially enabling attackers to bypass security controls implemented by the IMA subsystem. When integer overflow occurs during measurement appraisal, it can corrupt memory structures or cause unexpected execution paths that may allow adversaries to circumvent integrity verification mechanisms. This undermines the fundamental security guarantees provided by the IMA framework, which is designed to ensure that system components have not been tampered with and that measurements are properly validated before being accepted as trustworthy. The vulnerability affects systems that rely on IMA for security policy enforcement, potentially allowing attackers to inject malicious measurements or manipulate the appraisal process to bypass security checks that should prevent unauthorized modifications to critical system files.
Mitigation strategies for this vulnerability require immediate kernel updates to address the integer overflow condition in the ima_appraise_measurement function. System administrators should prioritize applying the relevant security patches that fix the improper handling of negative return codes from evm_verifyxattr() and implement proper bounds checking before arithmetic operations are performed. Organizations should also consider implementing additional monitoring for anomalous IMA behavior or measurement failures that could indicate exploitation attempts. The fix typically involves adding proper validation checks to ensure that return codes are within expected ranges before they are processed, preventing the conditions that lead to integer overflow. From an ATT&CK perspective, this vulnerability could be leveraged by adversaries seeking to perform privilege escalation or maintain persistence through manipulation of system integrity measurements, making it a significant concern for organizations implementing security controls based on IMA and EVM frameworks.