APACHE WEB SERVER — ARCHITECTURE (EXAM CRITICAL)
Apache Core Architecture
| Component | Memorize Exactly |
| Apache HTTP Server | Open-source web server developed by Apache Software Foundation |
| Process Model | Multi-process or multi-threaded |
| Request Handling | Uses child processes or threads |
| Configuration Files | httpd.conf, apache2.conf |
| Modules | Extend server functionality |
MEMORY HOOK:
Apache = process-based + modular
Apache Process Models (VERY IMPORTANT)
| Model | Description |
| Prefork MPM | Multiple child processes, one request per process |
| Worker MPM | Multiple threads per process |
| Event MPM | Optimized worker model handling keep-alive connections |
MEMORY HOOK:
Prefork = process | Worker = threads | Event = optimized worker
Apache Modules (EXAM FAVORITE)
| Module | Purpose |
| mod_ssl | Enables SSL/TLS support |
| mod_rewrite | URL rewriting |
| mod_proxy | Reverse proxy functionality |
| mod_auth | Authentication and authorization |
| mod_cgi | Executes CGI scripts |
| mod_headers | Manipulates HTTP headers |
MEMORY HOOK:
SSL, Rewrite, Proxy, Auth, CGI, Headers
APACHE VULNERABILITIES (DO NOT SKIP)
Common Apache Vulnerabilities
| Vulnerability | Memorize |
| Misconfigured permissions | Unauthorized file access |
| Directory listing enabled | Sensitive file exposure |
| Default/sample files | Information disclosure |
| mod_cgi misconfiguration | Command execution |
| mod_proxy abuse | SSRF |
| Weak SSL configuration | MITM |
| Verbose error messages | Recon advantage |
Apache Attack Surface Summary
| Attack Vector | Result |
| Directory traversal | Access outside web root |
| File inclusion | Code execution |
| Buffer overflow | DoS / RCE |
| Misconfigured modules | Privilege escalation |
MEMORY HOOK:
Apache breaks via modules + misconfig
IIS Core Components
| Component | Purpose |
| IIS | Microsoft web server |
| Application Pool | Isolates web applications |
| Worker Process (w3wp.exe) | Handles requests |
| web.config | IIS configuration file |
| inetmgr | IIS management console |
MEMORY HOOK:
IIS = App Pool isolation
IIS Request Flow
| Step | Memorize |
| Client sends HTTP request | Entry point |
| IIS receives request | Listener |
| Assigned to App Pool | Isolation |
| w3wp.exe processes request | Execution |
| Response returned | Client |
IIS VULNERABILITIES (FULL LIST)
Common IIS Misconfigurations
| Vulnerability | Result |
| Directory browsing enabled | Sensitive file exposure |
| Unrestricted file upload | Web shell |
| Weak NTFS permissions | Privilege escalation |
| web.config exposure | Credential leakage |
| Default ISAPI filters | RCE |
| Verbose errors | Recon |
IIS Attack Surface Summary
| Vector | Impact |
| File upload | Shell execution |
| Config exposure | Full compromise |
| Permission flaws | SYSTEM access |
| Legacy components | Exploitable services |
MEMORY HOOK:
IIS fails via config + permissions
NGINX WEB SERVER — ARCHITECTURE (RECAP FOR MEMORY)
Nginx Core Design
| Feature | Memorize |
| Architecture | Master–worker |
| Worker Model | Single-threaded |
| I/O Model | Event-driven, non-blocking |
| Role | Web server, reverse proxy, load balancer |
Nginx Components
| Component | Function |
| Master Process | Controls workers |
| Worker Processes | Handle client requests |
| Proxy Cache | Stores cached content |
| Cache Loader | Loads cache at startup |
| Cache Manager | Removes expired cache |
MEMORY HOOK:
Master controls, workers serve
NGINX VULNERABILITIES (FULL LIST)
| Vulnerability | Impact |
| NULL pointer dereference (HTTP/3) | DoS / RCE |
| SSRF | Internal network access |
| RCE via Nginx-UI | Full compromise |
| Improper certificate validation | File write |
| SQL injection | Data breach |
| Unauthenticated private key access | TLS compromise |
| HTTP/2 memory exhaustion | DoS |
| OS command injection | Remote execution |
| Default file permissions | Sensitive modification |
PART 3 NEXT (CONFIRMED)