CVE-2001-0004 — AI Deep Analysis Summary

🚨 **Essence**: IIS 4.0/5.0 leaks source code via URL manipulation. 📉 **Consequences**: Attackers read `.htr` ISAPI extension files, exposing sensitive web server program source code.…

🛠️ **Root Cause**: Improper handling of URL fragments combined with `.htr` extension parsing. 🔍 **Flaw**: The server incorrectly interprets `%3F+.htr` in URLs, allowing access to restricted files.…

🖥️ **Affected**: Microsoft IIS 5.0 and IIS 4.0. 📦 **Component**: Web Server ISAPI Extensions. 🚫 **Vendor**: Microsoft (n/a in metadata).

🕵️ **Action**: Read executable web server program source code. 🔓 **Privileges**: Remote unauthenticated access. 📂 **Data**: Sensitive internal logic and configuration details hidden in `.htr` files.

🔓 **Auth**: None required. Remote attackers can exploit it directly. ⚙️ **Config**: Depends on `.htr` extension being enabled/accessible. 🚀 **Threshold**: Low. Simple URL string manipulation.

📢 **Public Exp**: Yes. Referenced in Bugtraq mailing list (20010108). 📜 **PoC**: `%3F+.htr` URL pattern. 🌍 **Wild Exploitation**: Documented in security databases (BID 2313, X-Force 5903).

🔍 **Check**: Scan for IIS 4.0/5.0 versions. 🧪 **Test**: Send requests with `%3F+.htr` suffix. 👀 **Indicator**: Look for source code return instead of 403/404 errors.…

🛡️ **Fix**: Yes. MS01-004 Security Bulletin released. 📅 **Date**: Published 2001-09-18. 📝 **Action**: Apply Microsoft security updates immediately.

🚧 **Workaround**: Disable `.htr` ISAPI extension if not needed. 🚫 **Block**: Restrict access to `.htr` files via IIS permissions. 🛑 **Mitigation**: Remove unnecessary extensions from web server configuration.

🔥 **Urgency**: HIGH (Historically). ⚖️ **Priority**: Critical for legacy systems. 📉 **Current**: Low for modern systems (IIS 4/5 are obsolete), but vital for maintaining old infrastructure.…