Apache Log4j2 - RCE (CVE-2021-44228)

CVE-2021-44228 is a critical remote code execution vulnerability in Apache Log4j2, often referred to as “Log4Shell.” It allows attackers to exploit JNDI lookups within log messages, enabling arbitrary code execution when crafted data is logged by affected systems.

CrowdSec has been tracking this vulnerability and its exploits since 10th of December 2021.

Based on data from the CrowdSec network, nearly all observed exploitation of CVE-2021-44228 is fully opportunistic, with attackers indiscriminately scanning the entire internet. These attacks are automated and lack any form of target selection or reconnaissance. Data from the CrowdSec community also indicates a gradual decrease in attacks targeting CVE-2021-44228. While still present in the wild, exploitation levels have dropped noticeably week-over-week. This may signal that the vulnerability is becoming less relevant or that defenses are improving fast enough for attackers to lose interest.

Observed attacks typically involve injection patterns in the request path that contain variations of ${jndi:, reflecting the core technique used to trigger the remote code execution condition.