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.
The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Hotpatch | Amazon | * | 1.3.5 (excluding) |
A race condition occurs within concurrent environments, and it is effectively a property of a code sequence. Depending on the context, a code sequence may be in the form of a function call, a small number of instructions, a series of program invocations, etc. A race condition violates these properties, which are closely related:
A race condition exists when an “interfering code sequence” can still access the shared resource, violating exclusivity. The interfering code sequence could be “trusted” or “untrusted.” A trusted interfering code sequence occurs within the product; it cannot be modified by the attacker, and it can only be invoked indirectly. An untrusted interfering code sequence can be authored directly by the attacker, and typically it is external to the vulnerable product.