How to recover a damaged archive?

Question

Data archiving

Good evening.
The organization caught a cryptolocker who encrypted part of the data. Backup via Cobian Backup was "configured", but when I try to open the archive I get a message that the archive is corrupted. Tried through several archivers - does not help. I found programs for "recovery" - they did not help.
Archive in 7zip format.
If you need any data on the archive, then tell me - I will provide it.
Thank you.

Answer 1

Archive in 7zip format.

The first two bytes of your archive file are 7z?

Answer 2

Just a week ago, I ran into the problem of unopenable 7zip archives made by Cobian. Unfortunately, these archives cannot be restored. According to the recipes from the official site, I pulled out 4GB of information from the 16 GB source data from the archive. And in another way, through the decryption of the LZMA stream, I received the same 4GB.
The problem is this: when creating an archive, Cobian writes a temporary file, the size of the archive itself, to the C drive in the TEMP folder. And if the space on disk C is less than the size of the archive (or quoting is enabled), then Cobian throws an Error in the log, but continues the operation of archiving and further copying the archive to the target storage. This creates an archive of the required weight, but it is impossible to open it, since inside it contains a "porridge" of pieces of LZMA streams of about 1, 1.5 MB each, well, in my case, the first stream is 4 GB.

Answer 3

It was compressed via ZIP and the archives did not open either.
It was possible to open only through the regular Corbian unarchiver: C:\Program Files (x86)\Cobian Backup 11\cbDecompressor.exe