CVE-2021-31805 — AI Deep Analysis Summary

🚨 **Essence**: Apache Struts 2 allows forced OGNL evaluation in tag attributes using untrusted input. 💥 **Consequences**: Remote Code Execution (RCE) & severe security degradation.

🛡️ **Root Cause**: CWE-917 (Improper Neutralization of Special Elements in Dynamic Code Evaluation). The flaw is in incomplete fixes for S2-061, allowing OGNL expressions in specific tag attributes.

📦 **Affected**: Apache Struts versions **2.0.0 to 2.5.29**. Vendor: Apache Software Foundation.

🔓 **Attacker Capabilities**: Full RCE. Hackers can execute arbitrary commands, read sensitive files (e.g., /etc/passwd), and potentially get reverse shells. No privilege escalation needed beyond web server context.

⚡ **Exploitation Threshold**: **LOW**. No authentication required. Exploitation relies on sending malicious HTTP requests with crafted parameters (e.g., `id` or `name`).

🌍 **Public Exp?**: **YES**. Multiple PoCs and Exploits are public on GitHub (e.g., S2-062 tools, Python scripts, Pocsuite modules). Wild exploitation is highly likely.

🔍 **Self-Check**: Use automated scanners or Python scripts (like `Struts2_S2-062_CVE-2021-31805.py`) to test target URLs. Look for OGNL injection points in action parameters.

✅ **Official Fix**: **YES**. Upgrade to Apache Struts **2.5.30** or later. The vulnerability is patched in newer versions.

🚧 **No Patch Workaround**: If upgrading isn't possible, implement strict WAF rules to block OGNL syntax (`#`, `@`, `new`) in user inputs. Sanitize all tag attribute inputs rigorously.

🔥 **Urgency**: **CRITICAL**. High severity, easy exploitation, and public exploits exist. Patch immediately to prevent RCE and data breach.