T09 · Insecure Skill Coding Practices
Warning
- Location
- scripts/analyze.js:51
- Finding
- Terminal Escape-Sequence Injection Through an Untrusted URL Argument<![CDATA[ ## Vulnerability Details **File Location**: `scripts/analyze.js`, lines 3 and 51 **Vulnerability Type**: Untrusted terminal output / terminal escape-sequence injection **Risk Level**: Medium ### Vulnerable Code ```js const url = process.argv[2]; // Get URL from command line arguments ``` The untrusted value is passed to `analyzeNews` and subsequently printed without validation or sanitization: ```js console.log(`Simulated analysis for: ${articleUrl}`); ``` ### Technical Analysis The command-line argument is attacker-controlled and is written verbatim to an ANSI-capable terminal. The program does not validate that the argument is a legitimate HTTP or HTTPS URL, nor does it remove terminal control characters before displaying it. An attacker can provide an argument containing embedded C0, C1, ESC, CSI, or OSC control sequences. When the value is printed, a compatible terminal may interpret these bytes as terminal commands instead of displaying them as ordinary text. Potential operations depend on the terminal emulator and its security configuration, but may include: - Altering colors, cursor location, or terminal state. - Clearing or rewriting visible terminal output. - Forging prompts, status messages, or audit results. - Creating misleading hyperlinks. - Attempting OSC-based clipboard modification where supported. - Concealing part of the supplied URL or subsequent output. The script intentionally emits ANSI formatting elsewhere, demonstrating that its expected output environment may interpret terminal escape sequences. ### Attack Path 1. An attacker prepares a URL-like command-line value containing embedded terminal control sequences. 2. The attacker persuades a user or automated workflow to invoke the analyzer with that value, for example: ```bash node scripts/analyze.js "$ATTACKER_CONTROLLED_VALUE" ``` 3. Line 3 stores the complete untrusted argument without validation. 4. The argument is passed into `analyzeNews`. 5. Line 5 ...[truncated 1182 chars]
- Remediation
- <![CDATA[ ## Remediation Suggestions 1. Parse and validate the input before use, accepting only absolute `http:` and `https:` URLs: ```js function validateArticleUrl(value) { let parsed; try { parsed = new URL(value); } catch { throw new Error("The supplied value is not a valid URL."); } if (!["http:", "https:"].includes(parsed.protocol)) { throw new Error("Only HTTP and HTTPS URLs are supported."); } return parsed.href; } ``` 2. Reject terminal control characters before parsing or displaying the value: ```js function rejectControlCharacters(value) { if (/[\x00-\x1F\x7F-\x9F]/u.test(value)) { throw new Error("The URL contains prohibited control characters."); } return value; } ``` 3. Use the validated, normalized URL throughout the program: ```js const rawUrl = process.argv[2]; if (!rawUrl) { console.error("Error: Please provide a URL to analyze."); process.exit(1); } let safeUrl; try { safeUrl = validateArticleUrl(rejectControlCharacters(rawUrl)); } catch (error) { console.error(`Error: ${error.message}`); process.exit(1); } analyzeNews(safeUrl); ``` 4. If arbitrary text must ever be displayed, encode non-printable characters into visible escaped notation rather than emitting the original bytes. 5. Apply the same sanitization to error messages and any future article-derived fields before writing them to interactive terminals or logs. 6. Add regression tests containing ESC, CSI, OSC, carriage-return, newline, backspace, and delete characters to verify that unsafe input is rejected or safely escaped. ]]>