🛡️ Sentinel: [CRITICAL] Fix command injection in PowerShell computer input#280
🛡️ Sentinel: [CRITICAL] Fix command injection in PowerShell computer input#280Dexploarer wants to merge 1 commit intodevelopfrom
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Summary of ChangesHello, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed! This pull request resolves a critical command injection vulnerability that could allow attackers to execute arbitrary PowerShell commands on the host system. The fix involves a fundamental change in how user input is handled when interacting with PowerShell, moving from a vulnerable escaping method to a secure Base64 encoding and decoding process. This significantly enhances the security posture of the application's interaction with the Windows sandbox environment. Highlights
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| const base64 = Buffer.from(text).toString("base64"); | ||
| runCommand( | ||
| "powershell", | ||
| [ | ||
| "-Command", | ||
| `Add-Type -AssemblyName System.Windows.Forms; [System.Windows.Forms.SendKeys]::SendWait('${escaped}')`, | ||
| `Add-Type -AssemblyName System.Windows.Forms; $decoded = [System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String('${base64}')); [System.Windows.Forms.SendKeys]::SendWait($decoded)`, | ||
| ], | ||
| 10000, | ||
| ); |
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Potential PowerShell Command Injection Risk
While the use of base64 encoding for the text minimizes the risk of injection, the base64 string is interpolated directly into the PowerShell command string. Although base64 encoding should not produce single quotes, it is best practice to ensure that the interpolated string cannot break out of the intended command context. Consider using double quotes around the base64 string in PowerShell, or further escaping, to ensure that even malformed or unexpected input cannot alter the command structure.
Recommended solution:
- Use double quotes around the base64 string in the PowerShell command, or validate/escape the string to ensure it cannot break the command context.
- Example:
`...FromBase64String(\"${base64}\")...` - Alternatively, use PowerShell's
-EncodedCommandparameter to avoid string interpolation entirely.
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Code Review
This pull request correctly fixes a critical command injection vulnerability in the performType and performKeypress functions by using Base64 encoding instead of string escaping. The approach is robust. My review includes a suggestion to refactor the duplicated code in these two functions to improve maintainability. While reviewing, I noticed that similar PowerShell command construction patterns exist elsewhere in the file. It would be beneficial to audit the entire file for similar patterns to ensure all potential command injection vectors are addressed comprehensively.
| const base64 = Buffer.from(text).toString("base64"); | ||
| runCommand( | ||
| "powershell", | ||
| [ | ||
| "-Command", | ||
| `Add-Type -AssemblyName System.Windows.Forms; [System.Windows.Forms.SendKeys]::SendWait('${escaped}')`, | ||
| `Add-Type -AssemblyName System.Windows.Forms; $decoded = [System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String('${base64}')); [System.Windows.Forms.SendKeys]::SendWait($decoded)`, | ||
| ], | ||
| 10000, | ||
| ); |
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The logic for executing SendKeys on Windows is nearly identical in performType and performKeypress (see lines 1149-1157). To improve maintainability and follow the DRY (Don't Repeat Yourself) principle, this logic should be extracted into a dedicated helper function. This function could accept the input string and timeout as parameters, and then be called from both performType and performKeypress.
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🚨 Severity: CRITICAL
💡 Vulnerability: Command injection vulnerability in
performTypeandperformKeypressvia unsanitized PowerShell commands execution when standard single-quote escaping is bypassed.🎯 Impact: Attackers who control the input string to the computer use API routes could potentially execute arbitrary PowerShell commands on the host sandbox Windows system by breaking out of the single quotes.
🔧 Fix: Substituted standard single-quote escaping mechanism with encoding arbitrary user input as a Base64 string in Node.js, and decoding it natively inside the PowerShell script block using
[System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String('${base64}')).✅ Verification: Code formatting and lint checks run cleanly (
@biomejs/biome check). Full test suite (bun test) passed. Journal added for future reference.PR created automatically by Jules for task 10261642245202175922 started by @Dexploarer