Sagemcom Router Insufficient Default PSK Entropy

Sagemcom F@st 5260 routers on firmware version 0.4.39 (and possibly others), in WPA mode, default to using a PSK that is generated from a 2-part wordlist of known values and a nonce with insufficient entropy. The number of possible PSKs is about 1.78 billion, which is too small.


MD5 | 1cbafac69bdd059b6ece817e1bd160df

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# Exploit Title: Sagemcom router insufficient default PSK entropy
# Date: 4-3-2019
# Exploit Author: Ryan Delaney
# Author Contact: [email protected]
# Author LinkedIn: https://www.linkedin.com/in/infosecrd/
# Vendor Homepage: https://www.sagemcom.com/
# Software Link: N/A
# Version: 0.4.39
# Tested on: 0.4.39
# CVE: CVE-2019-9555

1. Description

Sagemcom F@st 5260 routers on firmware version 0.4.39 (and possibly
others), in WPA mode, default to using a PSK that is generated from a
2-part wordlist of known values and a nonce with insufficient entropy. The
number of possible PSKs is about 1.78 billion, which is too small.

2. Wordlist / PoC

A txt file has been created that contains every possible default PSK. It
contains ~1.78 billion entries and is about 23.4 GB uncompressed.
A 582 MB compressed 7z archive containing this txt file is available here:
hxxps://drive[.]google[.]com/file/d/1PZ-enM6VO56tMzhl42OCPGpBiteSIVD-/view?usp=sharing

3. Mitigation

Change the default PSK key to a more secure key with greater entropy.
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