Cryptographic API Misuse Vulnerability

[lialon]

Description:

In the "DeDRM_tools/DeDRM_plugin/adobekey.py", "DeDRM_tools/DeDRM_plugin/androidkindlekey.py", "DeDRM_tools/DeDRM_plugin/ignobleepub.py" and "DeDRM_tools/DeDRM_plugin/ignoblepdf.py" etc.. I have identified security vulnerabilities about insecure cryptographic algorithm.

ECB mode encryption is not semantically secure, which means it might cause information leakage.

PKCS1v1.5 is vulnerable to the chosen-ciphertext attack.

AES-CBC with fixed or hardcode IV is vulnerable to the chosen-ciphertext attack.

DES and RC4 is disallowed or for legacy use only.

Location:

https://github.com/apprenticeharper/DeDRM_tools/blob/master/DeDRM_plugin/adobekey.py#L165

self._aes = _AES.new(key, _AES.MODE_CBC, b'\x00'*16)

https://github.com/apprenticeharper/DeDRM_tools/blob/master/DeDRM_plugin/androidkindlekey.py#L148

return DES.new(self.key, DES.MODE_CBC, self.iv)

https://github.com/apprenticeharper/DeDRM_tools/blob/master/DeDRM_plugin/ignobleepub.py#L168

self._aes = _AES.new(key, _AES.MODE_CBC, b'\x00'*16)

https://github.com/apprenticeharper/DeDRM_tools/blob/master/DeDRM_plugin/ignoblepdf.py#L203

self._arc4 = _ARC4.new(userkey)

https://github.com/apprenticeharper/DeDRM_tools/blob/master/DeDRM_plugin/ineptepub.py#L298

self._aes = _AES.new(key, _AES.MODE_CBC, b'\x00'*16)

https://github.com/apprenticeharper/DeDRM_tools/blob/master/DeDRM_plugin/ineptepub.py#L317

return _PKCS1_v1_5.new(self._rsa).decrypt(data, 172)

https://github.com/apprenticeharper/DeDRM_tools/blob/master/DeDRM_plugin/ineptpdf.py#L357

self._arc4 = _ARC4.new(userkey)

https://github.com/apprenticeharper/DeDRM_tools/blob/master/DeDRM_plugin/ineptpdf.py#L390

return _PKCS1_v1_5.new(self._rsa).decrypt(data, 172)

https://github.com/apprenticeharper/DeDRM_tools/blob/master/Obok_plugin/obok/obok.py#L255

self._aes = _AES.new(key, _AES.MODE_ECB)

https://github.com/apprenticeharper/DeDRM_tools/blob/master/Other_Tools/Kobo/obok.py#L249

self._aes = _AES.new(key, _AES.MODE_ECB)

Reference

• CWE-327: Use of a Broken or Risky Cryptographic Algorithm
• CWE-330: Use of Insufficiently Random Values
• RFC7465 - Prohibiting RC4 Cipher Suites(https://www.rfc-editor.org/rfc/rfc7465)
• https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-131Ar2.pdf

Recommendate

• Generate IV with cryptographic secure PRNG.

• Use other cipher mode such as CFB or CTR with random IV.

• Generate IV with cryptographic secure PRNG.

[ElleKayEm]

These vulnerabilities are in Adobe, Amazon, Kobo, and B&N's encryption which this plugin decrypts.