# Course 38 - Web Security Known Web Attacks | Episode 1: Guide to Remote Command Injection Page: https://stenobird.com/podcast/cybercode-academy-7578615/course-38-web-security-known-web-attacks-episode-1-guide-to-remote-command-injection Text version: https://stenobird.com/podcast/cybercode-academy-7578615/course-38-web-security-known-web-attacks-episode-1-guide-to-remote-command-injection.md Podcast: [CyberCode Academy](https://stenobird.com/podcast/cybercode-academy-7578615) Published: 2026-07-02T06:00:03+00:00 Episode link: https://www.spreaker.com/episode/course-38-web-security-known-web-attacks-episode-1-guide-to-remote-command-injection--72711314 Audio file: https://dts.podtrac.com/redirect.mp3/api.spreaker.com/download/episode/72711314/how_one_semicolon_hijacks_your_server.mp3 Processing state: not_requested JSON: https://stenobird.com/v1/public/podcasts/cybercode-academy-7578615/episodes/course-38-web-security-known-web-attacks-episode-1-guide-to-remote-command-injection Duration seconds: 1168 ## Resource In this lesson, youโ€™ll learn about: Remote Command Execution (RCE), blind exploitation techniques, and defensive strategies against command injection1. What is Remote Command Execution (RCE)๐Ÿ”น Definition: A vulnerability where user input is executed as an OS command ๐Ÿ”น Common in: Python โ†’ os.system Node.js โ†’ exec PHP โ†’ shell_exec ๐Ÿ‘‰ Key Insight RCE = user controls what the server executes2. Root Cause of RCE๐Ÿ”น Problem: Untrusted input passed directly into system commands ๐Ÿ”น Example:ping 127.0.0.1 ๐Ÿ”น Vulnerable usage:ping ๐Ÿ‘‰ Key Insight No validation = full command injection risk3. Command Injection via Delimiters๐Ÿ”น Common delimiter: ; โ†’ separates commands ๐Ÿ”น Example attack:127.0.0.1; ls ๐Ÿ‘‰ Result: First command runs Second command executes attacker payload ๐Ÿ‘‰ Key Insight Delimiters allow attackers to chain commands4. Other Command Operators๐Ÿ”น Logical operators: && โ†’ run if first succeeds || โ†’ run if first fails & โ†’ run in background | โ†’ pipe output ๐Ÿ‘‰ Key Insight Filtering one operator โ‰  blocking exploitation5. Blind RCE (No Output Scenario)๐Ÿ”น Problem: Application does NOT return command output ๐Ÿ”น Solution: Use timing-based detection ๐Ÿ”น Example:ping -c 10 127.0.0.1 ๐Ÿ‘‰ Observation: Response delay confirms execution ๐Ÿ‘‰ Key Insight Time delays = proof of execution6. Detection Strategy๐Ÿ”น Steps: Inject payload Monitor response time Compare delays ๐Ÿ‘‰ Key Insight Blind RCE โ‰ˆ Blind SQL Injection (time-based)7. Filter Evasion Techniques (High-Level)๐Ÿ”น Problem: Input filters block simple payloads ๐Ÿ”น General bypass ideas: Use alternative separators Change encoding (e.g., newline %0A) Modify payload structure ๐Ÿ‘‰ Key Insight Defense must be comprehensive, not pattern-based8. Injection Context Matters๐Ÿ”น Input placement: Beginning of command Middle of command End of command ๐Ÿ‘‰ Each requires diffeโ€ฆ ## Actions - request_transcript: `POST https://stenobird.com/v1/public/podcasts/cybercode-academy-7578615/episodes/course-38-web-security-known-web-attacks-episode-1-guide-to-remote-command-injection/transcription-requests` โ€” Idempotently request low-priority transcript generation for this episode. - read_markdown: `GET https://stenobird.com/podcast/cybercode-academy-7578615/course-38-web-security-known-web-attacks-episode-1-guide-to-remote-command-injection.md` โ€” Read the agent-friendly Markdown representation of this episode resource. A page view does not enqueue transcription. Agents should invoke `request_transcript` explicitly when they need this episode processed. ## Transcript Full transcripts are not published on public pages unless there is a clear rights basis.