CVE-2022-33915 in AWS Apache Log4j Hotpatch Package
Summary
by MITRE • 06/17/2022
Versions of the Amazon AWS Apache Log4j hotpatch package before log4j-cve-2021-44228-hotpatch-1.3.5 are affected by a race condition that could lead to a local privilege escalation. This Hotpatch package is not a replacement for updating to a log4j version that mitigates CVE-2021-44228 or CVE-2021-45046; it provides a temporary mitigation to CVE-2021-44228 by hotpatching the local Java virtual machines. To do so, it iterates through all running Java processes, performs several checks, and executes the Java virtual machine with the same permissions and capabilities as the running process to load the hotpatch. A local user could cause the hotpatch script to execute a binary with elevated privileges by running a custom java process that performs exec() of an SUID binary after the hotpatch has observed the process path and before it has observed its effective user ID.
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Analysis
by VulDB Data Team • 06/17/2022
The vulnerability identified as CVE-2022-33915 affects Amazon AWS Apache Log4j hotpatch packages version prior to log4j-cve-2021-44228-hotpatch-1.3.5 and represents a critical race condition that enables local privilege escalation. This issue emerges within the context of the broader log4j vulnerability landscape, specifically addressing CVE-2021-44228 and CVE-2021-45046 which together constitute the well-known log4shell exploits. The hotpatch mechanism was designed as a temporary workaround while organizations migrate to patched log4j versions, but this particular implementation introduces a dangerous flaw in its operational methodology.
The technical flaw manifests through a race condition inherent in the hotpatch script's process enumeration and privilege handling mechanism. The hotpatch package operates by iterating through all running Java processes and performing a series of checks before executing the Java virtual machine with identical permissions and capabilities as the target process. This approach is fundamentally flawed because it creates a temporal window where the script can observe a process path and subsequently execute operations before the effective user ID has been fully established. The race condition occurs between the observation of the process path and the verification of its effective user privileges, allowing malicious actors to exploit this window.
The operational impact of this vulnerability is severe and directly enables local privilege escalation attacks. A local user can craft a custom java process that executes an SUID binary after the hotpatch script has already observed the process path but before it has verified the effective user ID. This exploitation technique leverages the timing gap in the hotpatch implementation to gain elevated privileges, potentially allowing attackers to execute arbitrary code with higher privileges than initially intended. The vulnerability specifically targets systems where the hotpatch mechanism is actively running and monitoring Java processes, making it particularly dangerous in environments with active log4j vulnerability management.
This vulnerability aligns with CWE-362, which describes race conditions in software implementations, and represents a classic example of timing-based privilege escalation flaws. The ATT&CK framework categorizes this under privilege escalation techniques, specifically leveraging process manipulation and timing attacks to bypass security controls. Organizations implementing this hotpatch mechanism face significant risk as the vulnerability essentially undermines the intended security boundaries of the patching process itself. The flaw demonstrates how temporary mitigation strategies can introduce new attack vectors when not properly designed with concurrency and timing considerations.
Mitigation strategies should prioritize immediate upgrade to log4j versions that properly address CVE-2021-44228 and CVE-2021-45046, as the hotpatch should never be considered a permanent solution. Organizations must ensure the hotpatch package is updated to version 1.3.5 or later, which contains fixes for the race condition. System administrators should implement additional monitoring to detect unauthorized process creation patterns and consider disabling the hotpatch mechanism entirely if not actively required. The vulnerability highlights the importance of thorough security review for temporary patches and demonstrates how seemingly innocuous operational mechanisms can introduce critical security weaknesses when not properly engineered for concurrent execution scenarios.