CrowdSec
6/10CrowdSec Score

Apache Log4j2 - RCE (CVE-2021-44228)

Published on10-12-2021
First seen on10-12-2021

8635Exploiting IPs reported

Apache Log4j2 2.0-beta9 through 2.15.0 (excluding security releases 2.12.2, 2.12.3, and 2.3.1) JNDI features used in configuration, log messages, and parameters do not protect against attacker controlled LDAP and other JNDI related endpoints. An attacker who can control log messages or log message parameters can execute arbitrary code loaded from LDAP servers when message lookup substitution is enabled. From log4j 2.15.0, this behavior has been disabled by default. From version 2.16.0 (along with 2.12.2, 2.12.3, and 2.3.1), this functionality has been completely removed. Note that this vulnerability is specific to log4j-core and does not affect log4net, log4cxx, or other Apache Logging Services projects.

CrowdSec analysis

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.

CrowdSec network data shows that most actors exploiting CVE-2021-44228 rely on broad, untargeted scans with minimal filtering. The activity is largely automated and opportunistic in nature. Additionally, according to week-over-week analysis by CrowdSec, exploitation of CVE-2021-44228 is surging. Attack volumes are spiking well above historical norms, indicating widespread and escalating interest from threat actors. CVE-2021-44228 is currently experiencing high visibility and active exploitation across the internet.

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.

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Protection

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Blocklist

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