This PR is meant to fix an arbitrary file write vulnerability, that can be
achieved using a specially crafted zip archive, that holds path traversal
filenames. When the filename gets concatenated to the target extraction
directory, the final path ends up outside of the target folder.
A sample malicious zip file named Zip.Evil.zip was used,
and when running the code below, resulted in the creation of C:/Temp/evil.txt
outside of the intended target directory.
There are various possible ways to avoid this issue, some include checking
for .. (dot dot) characters in the filename, but the best solution in our
opinion is to check if the final target filename, starts with the target
folder (after both are resolved to their absolute path).
Stay secure,
Snyk Team
* First pass. Writing isn't implemented on stream. Tests are busted.
* LZipReader works...no file name :(
* LZipWriter works
* Writing tests are actually correct now. LZipStream correctly writes trailer now. lzip command line tool likes it.
* Add recommendation blurb
* Update notes for formats
* LZip isn't an archive format
* Attempting to fix and implement crc32
* LZip writing test passes
* Had to invert crc to check uncompressed data.
