We have broken SHA-1 in practice

3 months ago

SHA-1 has been practically broken, allowing for the creation of two colliding PDF files with the same digital signature.
This vulnerability affects digital signatures, file integrity verification, and file identification across various applications, including GIT and SVN.
Many applications still use SHA-1 despite known theoretical attacks since 2005 and its deprecation by NIST in 2011.
Google and Mozilla have taken steps to protect users, with Chrome marking SHA-1 certificates as insecure and Firefox deprecating SHA-1.
GIT repositories can be manipulated to have the same commit hash but different contents, posing a security risk.
SVN has been patched against SHA-1 collisions in versions 1.9.6 and up, and 1.8.18.
The SHAttered attack is significantly faster than brute force, requiring extensive computational resources but is now practical.
A collaboration between CWI and Google Research led to this breakthrough, leveraging Google's infrastructure and expertise.
An online tool is available to check files for SHA-1 collision attacks, developed by Marc Stevens and Dan Shumow.
Counter-cryptanalysis can detect and mitigate SHA-1 collision attacks by producing different hashes for colliding files.

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