Recovery damaged dump file

Hi.

My PostgreSQL server was affect by a Ransomware virus. I'm trying to
restore the database from a dump file made by pg_dump in custom format (-F
c option), but the dump file seems to be damaged in the first's 1000 lines.

Opening the file with vi shows ^(at)^@^(at)^@^(at)^@^(at)^@^(at)^@^ followed by part of
the databse schema and the a lote of lines with binary characters that i
think is the table's data.

I tried to replace those first lines with lines from other dev database and
i can run pg_restore but at some point throws error.

pg_restore db.backup > out.sql

pg_restore: [custom archiver] unrecognized data block type (0) while
searching archive

The follow commands works fine:
pg_restore -s db.backup > out.sql
pg_restore -l db.backup

Do you think it's possible to recover the dump file, is there any method or
tool to recover dump files?

Thanks.
Mário