Sometimes I miss that land of bliss.
We are given an archive with dbx file.
I've Installed undbx - a tool to extract e-mails from Outlook Express .dbx files.
Performed unbase64 and got a file, with TAPE header (Microsoft tape format).
Downloaded and built mtftar - a tool for translating a MTF stream to a TAR stream.
./mtftar -v -f out.mtf | tar xfv -
Found a file flag.doc, where image with flag was inserted.
And got a flag: