There are several variants of CryptoWall but it does not change the file extension of the file it encrypts.. The original CryptoWall leaves files (ransom notes) with names like DECRYPT_INSTRUCTION.TXT, DECRYPT_INSTRUCTION.HTML, and DECRYPT_INSTRUCTION.URL. CryptoWall 2.0 leaves ransom notes named install_tor.url. CryptoWall 3.0 leaves ransom notes named HELP_DECRYPT.TXT, HELP_DECRYPT.HTML, and HELP_DECRYPT.PNG CryptoWall 4.0 leaves ransom notes named HELP_YOUR_FILES.TXT, HELP_YOUR_FILES.HTML and HELP_YOUR_FILES.PNG. CryptoWall 4.0 will encrypt the actual filename of an encrypted file as well as the data contained in it. Each encrypted file will have a unique name with random characters (0ausbffwh.p5, 72lcvn.iv6nn, x83o8x.ux7, etc) as described here.
A repository of all current knowledge regarding CryptoWall, CryptoWall 2.0, CryptoWall 3.0 & CryptoWall 4.0 is provided by Grinler (aka Lawrence Abrams), in this topic: CryptoWall and DECRYPT_INSTRUCTION Ransomware Information Guide and FAQ
Unfortunately at this time there is no fix tool and decryption of CryptoWall files...is impossible since there is no way to retrieve the private key that can be used to decrypt your files without paying the ransom. For a more detailed explanation, read this reply by Nathan (DecrypterFixer).
The only methods you have of restoring your files is explained in the FAQ: How to restore files encrypted by CryptoWall...but there is no guarantee that will work. As with most ransomware infections...the best solution for dealing with encrypted data is to restore from backups. If that is not a viable option, the only other alternative is to save your data as is and wait for a possible breakthrough...meaning, what seems like an impossibility at the moment (decryption of your data), there is always hope someday there may be a potential solution so save the encrypted data and wait until that time.
There are ongoing discussions in these topics where you can ask questions and seek further assistance for the CryptoWall variant you are dealing with.
Rather than have everyone start individual topics, it would be best (and more manageable for staff) if you posted any questions, comments or requests for assistance in the topic discussion related to the variant you are dealing with. Doing that will also ensure you receive proper assistance from our crypto malware experts since they may not see this thread. To avoid unnecessary confusion...this topic is closed.
The BC Staff