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Detected RC4 cipher algorithm which is considered insecure. The algorithm has many known vulnerabilities. Use AES instead.
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rules: - id: insecure-cipher-algorithm-rc4 message: Detected RC4 cipher algorithm which is considered insecure. The algorithm has many known vulnerabilities. Use AES instead. metadata: source-rule-url: https://github.com/PyCQA/bandit/blob/d5f8fa0d89d7b11442fc6ec80ca42953974354c8/bandit/blacklists/calls.py#L84 cwe: "CWE-327: Use of a Broken or Risky Cryptographic Algorithm" owasp: "A3: Sensitive Data Exposure" bandit-code: B304 references: - https://crypto.stackexchange.com/questions/853/google-is-using-rc4-but-isnt-rc4-considered-unsafe - https://sweet32.info/ category: security technology: - pycryptodome license: Commons Clause License Condition v1.0[LGPL-2.1-only] severity: WARNING languages: - python pattern-either: - pattern: Cryptodome.Cipher.ARC4.new(...) - pattern: Crypto.Cipher.ARC4.new(...)
# cf. https://github.com/PyCQA/bandit/blob/b78c938c0bd03d201932570f5e054261e10c5750/examples/ciphers.py from Crypto.Cipher import AES from Crypto.Cipher import ARC2 as pycrypto_arc2 from Crypto.Cipher import ARC4 as pycrypto_arc4 from Crypto.Cipher import Blowfish as pycrypto_blowfish from Crypto.Cipher import DES as pycrypto_des from Crypto.Cipher import XOR as pycrypto_xor from Cryptodome.Cipher import ARC2 as pycryptodomex_arc2 from Cryptodome.Cipher import ARC4 as pycryptodomex_arc4 from Cryptodome.Cipher import Blowfish as pycryptodomex_blowfish from Cryptodome.Cipher import DES as pycryptodomex_des from Cryptodome.Cipher import XOR as pycryptodomex_xor from Crypto.Hash import SHA from Crypto import Random from Crypto.Util import Counter key = b'Sixteen byte key' iv = Random.new().read(pycrypto_arc2.block_size) # ruleid:insecure-cipher-algorithm-rc2 cipher = pycrypto_arc2.new(key, pycrypto_arc2.MODE_CFB, iv) msg = iv + cipher.encrypt(b'Attack at dawn') # ruleid:insecure-cipher-algorithm-rc2 cipher = pycryptodomex_arc2.new(key, pycryptodomex_arc2.MODE_CFB, iv) msg = iv + cipher.encrypt(b'Attack at dawn') key = b'Very long and confidential key' nonce = Random.new().read(16) tempkey = SHA.new(key+nonce).digest() # ruleid:insecure-cipher-algorithm-rc4 cipher = pycrypto_arc4.new(tempkey) msg = nonce + cipher.encrypt(b'Open the pod bay doors, HAL') # ruleid:insecure-cipher-algorithm-rc4 cipher = pycryptodomex_arc4.new(tempkey) msg = nonce + cipher.encrypt(b'Open the pod bay doors, HAL') iv = Random.new().read(bs) key = b'An arbitrarily long key' plaintext = b'docendo discimus ' plen = bs - divmod(len(plaintext),bs) padding = [plen]*plen padding = pack('b'*plen, *padding) bs = pycrypto_blowfish.block_size # ruleid:insecure-cipher-algorithm-blowfish cipher = pycrypto_blowfish.new(key, pycrypto_blowfish.MODE_CBC, iv) msg = iv + cipher.encrypt(plaintext + padding) bs = pycryptodomex_blowfish.block_size # ruleid:insecure-cipher-algorithm-blowfish cipher = pycryptodomex_blowfish.new(key, pycryptodomex_blowfish.MODE_CBC, iv) msg = iv + cipher.encrypt(plaintext + padding) key = b'-8B key-' plaintext = b'We are no longer the knights who say ni!' nonce = Random.new().read(pycrypto_des.block_size/2) ctr = Counter.new(pycrypto_des.block_size*8/2, prefix=nonce) # ruleid:insecure-cipher-algorithm-des cipher = pycrypto_des.new(key, pycrypto_des.MODE_CTR, counter=ctr) msg = nonce + cipher.encrypt(plaintext) nonce = Random.new().read(pycryptodomex_des.block_size/2) ctr = Counter.new(pycryptodomex_des.block_size*8/2, prefix=nonce) # ruleid:insecure-cipher-algorithm-des cipher = pycryptodomex_des.new(key, pycryptodomex_des.MODE_CTR, counter=ctr) msg = nonce + cipher.encrypt(plaintext) key = b'Super secret key' plaintext = b'Encrypt me' # ruleid:insecure-cipher-algorithm-xor cipher = pycrypto_xor.new(key) msg = cipher.encrypt(plaintext) # ruleid:insecure-cipher-algorithm-xor cipher = pycryptodomex_xor.new(key) msg = cipher.encrypt(plaintext) key = b'Sixteen byte key' # ok:insecure-cipher-algorithm-rc2 # ok:insecure-cipher-algorithm-rc4 # ok:insecure-cipher-algorithm-des # ok:insecure-cipher-algorithm-blowfish # ok:insecure-cipher-algorithm-xor cipher = AES.new(key, AES.MODE_EAX, nonce=nonce) plaintext = cipher.decrypt(ciphertext) try: cipher.verify(tag) print("The message is authentic:", plaintext) except ValueError: print("Key incorrect or message corrupted")
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