Your files indeed seem to contain uncrypted virus samples. In that case, we can’t do anything about it - please scramble your virus database properly.
[It’s possible that they are actually XORred by something - but if even the original malware file was XORred, you get the pure plaintext by using this “encryption”; so, something a bit stronger is needed.]
I know that the files are not PE files - but they still contain plaintext samples of malicious files.
I don’t know what “special algorithm” you mean, but the pieces detected by avast! don’t seem encrypted at all to me.
Unfortunatelly, a well-known problem of Panda not encrypting its signatures
Every virus can be identified, because it contains some unique signatures. Antiviral programs have their own database of that signatures. We call this database the "virus definition file". When an antiviral program scans a file for viruses, it compares all the signatures (of all viruses) in the database with the signatures in that file. If the signatures match (they are the same), the file is marked as infected. For an antivirus program, it is important to hide this database of signatures somehow - e.g. by encrypting it. Panda Antivirus does not encrypt its virus database - the signatures inside are clearly "visible" to other antiviral programs, so they detect this file as infected (but there is actually no virus inside - only the signatures are the same).
