A few days back I was looking for a tool to maintain my notes and important code snippets and I came across a tool called massCode.
About massCode
massCode is one of the free and open-source code snippet manager tool build with the electron. Sometime back it was in trending on GitHub and also listed on electron website https://www.electronjs.org/apps/masscode
massCode makrdown editor
You can select different programming languages to render respecting code snippets but my interest was in markdown editor. Here is a quick image of how massCode markdown editor works
XSS in massCode makrdown editor
Next, As usual, I tried to inject the script tag to see if it gets executed
But nothing happened.
Again i tried to inject <a> tag as shown in below image
and luckily it worked this time. easy-peasy
Code execution in massCode
Since massCode is built on electron and we have XSS vulnerability at the same time. I quickly navigate to the source code available on GitHub, and figured out that nodeIntegration flag is set to true.
which means we can invoke node API’s. Next I created a simple XSS payload to open a calculator on windows
<a href="javascript:try{ const {shell} = require('electron'); shell.openExternal('file:C:/Windows/System32/calc.exe') }catch(e){alert(e)}">aaaaaaa</a>
This issue has been fixed in latest relase of massCode
