david wong

Hey! I'm David, a security consultant at Cryptography Services, the crypto team of NCC Group . This is my blog about cryptography and security and other related topics that I find interesting.

[facebook bug bounty] Reading local files from facebook

posted December 2014

Josip Franjković found a vulnerability in one of the file uploader of facebook.

He described what he did here

basically he uploaded a zipped file of a symbolic link to /etc/passwd

ln -s /etc/passwd link
zip --symlinks test.zip link

And since uploaders are always a mess to secure. Facebook just replied displaying the content of what he thought was the unzipped resume.

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