CVE-2019-19050 in Linux
Summary
by MITRE
A memory leak in the crypto_reportstat() function in crypto/crypto_user_stat.c in the Linux kernel through 5.3.11 allows attackers to cause a denial of service (memory consumption) by triggering crypto_reportstat_alg() failures, aka CID-c03b04dcdba1.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 02/23/2024
The vulnerability described in CVE-2019-19050 represents a critical memory management flaw within the Linux kernel's cryptographic subsystem that can be exploited to achieve denial of service conditions. This issue resides in the crypto_user_stat.c file within the kernel's crypto framework and specifically affects the crypto_reportstat() function. The vulnerability manifests when attackers can trigger failures in the crypto_reportstat_alg() function, leading to uncontrolled memory consumption that ultimately results in system resource exhaustion. The affected kernel versions range from the earliest available through 5.3.11, indicating a significant timeframe of exposure that would have impacted numerous production systems.
The technical root cause of this vulnerability stems from improper memory management within the cryptographic statistics reporting mechanism. When the crypto_reportstat_alg() function encounters certain failure conditions, the memory allocated for cryptographic algorithm statistics reporting is not properly freed or released back to the system. This memory leak occurs repeatedly each time the failure condition is triggered, causing progressive memory consumption that can eventually exhaust available system resources. The vulnerability operates at the kernel level where memory management is critical and where improper handling can have cascading effects on system stability and performance. This type of memory leak falls under the CWE-401 category of "Improper Release of Memory Before Removing Last Reference" and represents a classic example of resource exhaustion through improper memory deallocation patterns.
The operational impact of this vulnerability extends beyond simple resource consumption, as it can be leveraged to create sustained denial of service conditions that may require system restarts to resolve. Attackers can repeatedly trigger the failure condition to continuously consume memory until system performance degrades significantly or complete system failure occurs. This vulnerability is particularly dangerous in server environments where cryptographic operations are frequent and where maintaining system availability is critical. The attack vector is relatively straightforward since it requires only the ability to trigger crypto_reportstat_alg() failures, which can be accomplished through carefully crafted inputs or by exploiting other vulnerabilities that lead to the specific failure conditions. The vulnerability aligns with ATT&CK technique T1499.004 "Fragging" which involves resource exhaustion attacks that consume system resources to prevent normal operations.
Mitigation strategies for this vulnerability must focus on both immediate patching and operational monitoring. The most effective solution involves applying the kernel patches released by the Linux kernel security team that address the memory leak in the crypto_reportstat() function. Organizations should prioritize updating to kernel versions 5.4.0 or later where the vulnerability has been resolved. Additionally, system administrators should implement monitoring for unusual memory consumption patterns that could indicate exploitation attempts. The vulnerability demonstrates the importance of proper memory management in kernel space and highlights the need for comprehensive testing of cryptographic subsystems under various failure conditions. Network defenders should also consider implementing intrusion detection systems that can identify patterns of repeated cryptographic operation failures that may indicate exploitation attempts. The fix implemented by the kernel maintainers ensures proper memory deallocation when cryptographic statistics reporting fails, preventing the accumulation of leaked memory blocks that would otherwise consume system resources indefinitely.