Avast Decryption Tool for LambdaLocker is designed to unlock LambdaLocker; a ransomware strain first spotted in May 2017.

LambdaLocker is written in Python programming language, and the currently common variant is decryptable.

Filename changes:
The ransomware adds the “.MyChemicalRomance4EVER” extension after a file name:
foobar.doc -> foobar.doc.MyChemicalRomance4EVER
document.dat -> document.dat.MyChemicalRomance4EVER

The ransomware also creates a text file named "UNLOCK_guiDE.txt" on the user's desktop as seen in the third screenshot below.