Full Report
Escaping input is very important when trying to prevent XSS, code injection and many other classes of vulnerabilities. However, the escaping is context dependent. In some situations, a single quote would break the system while, for other times, it may be another character. Knowing when to escape what really matters. In this report, a user is providing a URL that will be navigated to. For some reason, there is a multiline comment that is necessary for escape some input. /*{ url: 'https://example.com' }*/ is used within the parameters. In order to prevent code injection, they call quote to escape single and double quotes. The quote is not the only thing to worry about though. What about the comment? By ending the comment, an attacker can add their own code. For instance, the input https://example.com?q=*/.../* would escape the comment to add arbitrary content to the JavaScript. In particular, this appears to be a NodeJs environment. The final payload to escape the function call and execute JavaScript is as follows: Injection point: page.waitForNavigation(/*{ url: ' https://example.com'}*/), Payload: https://example.com?q=*/require(child_process) .exec(touch$IFS/tmp/haxx)/* Executed code: page.waitForNavigation(/*{ url: ' https://example.com?q=*/require(`child_process`) .exec(`touch$IFS/tmp/dee-see`)/*' }*/), A pretty interesting case of not escaping inputs properly. True code injection doesn't happen very often but it's sure interesting when it does. Good report!
Analysis Summary
# Vulnerability: JavaScript Comment Injection Leading to Code Execution in Node.js Context
## CVE Details
- CVE ID: N/A (Context does not provide a CVE)
- CVSS Score: N/A
- CWE: CWE-74: Improper Neutralization of Special Elements in Output Used by a Web Page ('Cross-site Scripting' or potentially CWE-94: Improper Control of Generation of Code ('Code Injection') due to the context)
## Affected Systems
- Products: Application utilizing Node.js environment functions like `page.waitForNavigation()` where user-supplied URL input is improperly sanitized within a JavaScript block containing multi-line comments (`/* ... */`).
- Versions: Not specified, context suggests a general implementation flaw related to improper context-aware escaping.
- Configurations: Environments where user input is directly concatenated into JavaScript code that uses C-style multi-line comments (like `/* ... */`) for structural purposes, especially during navigation or rendering steps.
## Vulnerability Description
The vulnerability arises from insufficient context-aware input sanitization when processing a user-supplied URL parameter (`q`) intended for a navigation function (e.g., `page.waitForNavigation`). While the system attempts to prevent Cross-Site Scripting (XSS) or injection by escaping single (`'`) and double quotes (`"`), it fails to account for the C-style multi-line comment delimiters (`/*` and `*/`).
An attacker can terminate the existing comment structure using the sequence `*/`, inject arbitrary JavaScript code, and then optionally start a new comment sequence (`/*`) to mask the remainder of the malicious payload and the expected end of the initial structure. The specific example payload leads to arbitrary command execution via Node.js features:
`https://example.com?q=*/require(child_process).exec(touch$IFS/tmp/haxx)/*` results in the final JavaScript execution:
`page.waitForNavigation(/*{ url: ' https://example.com?q=*/require(`child_process`) .exec(`touch$IFS/tmp/dee-see`)/*' }*/)`
This achieves **Code Injection** within the JavaScript context due to the successful termination of the intended comment block.
## Exploitation
- Status: PoC available (The article provides a specific working payload)
- Complexity: Low (Requires knowledge of C-style comment termination and Node.js execution context)
- Attack Vector: Input Injection into a controlled URL parameter.
## Impact
- Confidentiality: High (If the injected command executes code that accesses sensitive local files or network resources)
- Integrity: High (Arbitrary command execution allows modification or destruction of data/system state)
- Availability: High (Can lead to system instability or denial of service via executed commands)
## Remediation
### Patches
- No specific patch information is provided in the context. Patches would require developers to implement robust, context-aware output encoding/escaping tailored specifically for the JavaScript syntax being used (including comment delimiters).
### Workarounds
- **Strict Validation:** Validate the input to ensure it conforms strictly to expected URL formats and does not contain characters used for injection like `*`, `/`, or control characters when being placed into the JS structure.
- **Context-Specific Escaping:** If the input must be embedded within a string literal inside a JavaScript comment block, ensure that both string delimiters *and* comment delimiters are properly escaped or disallowed entirely.
## Detection
- Indicators of compromise: Look for URLs containing `*/` followed by executable code sequences (e.g., `require[...]`, `.exec(...)`) within application logs relating to navigation parameters.
- Detection methods and tools: Static analysis tools configured to detect poor string concatenation into interpreted code blocks, especially around known sensitive API calls like browser automation functions. Runtime monitoring for unexpected child process executions originating from web handling functions.
## References
- Vendor advisories: N/A
- Relevant links - defanged: N/A