Clam 2197 Fix PDF metadata decryption issues + Add support for checking empty owner password #1141
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The encrypted metadata may be stored in a <> block containing hex bytes. Strip off the <> and decode the hex to binary.
Specifically for algorithm 6 (/R 6). Use the O and OE strings to test if an empty owner password will decrypt the file.
Store temp files with obj id and gen id so analysts know which is which. Don't dump decoded objects immediately. They'll get dumped later at the end of pdf_extract_obj(). At the end of PDF object extraction, we don't need to find out the "dumpid" (aka the object index in our list of pdf objects). It isn't actually used! So I removed the unused parameter.
ragusaa
reviewed
Jan 17, 2024
ragusaa
approved these changes
Jan 17, 2024
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Fix PDF metadata decryption issues.
The encrypted metadata may be stored in a
<>-block containing hex bytes (not raw binary).Strip off the <> and decode the hex to binary before attempting to decrypt it.
PDF: Add support for checking empty owner password.
Specifically for algorithm 6 (/R 6). I have not attempted the same for older algorithms.
Use the O and OE strings to test if an empty owner password will decrypt the file.
The primary difference with checking the user password is the U-string is also concatenated when making the hashes to verify the key.