Sitecom WLM-3500 backdoor accounts
Title: Sitecom WLM-3500 backdoor accounts
Discovery date: 24/03/2013
Release date: 16/04/2013
Credits: Roberto Paleari ([email protected], @rpaleari)
Advisory URL: http://blog.emaze.net/2013/04/sitecom-wlm-3500-backdoor-accounts.html
Class: Authentication bypass
We confirm the presence of the security vulnerability on the following
* Sitecom WLM-3500, firmware versions < 1.07
Other device models and firmware versions are probably also vulnerable, but
they were not checked.
Sitecom WLM-3500 routers contain an undocumented access backdoor that can be
abused to bypass existing authentication mechanisms.
More in detail, attackers can access the web interface of the affected devices
using two distinct hard-coded users:
These hard-coded accounts are persistently stored inside the device firmware
image. Despite these users cannot access all the pages of the web interface,
they can still access page "/romfile.cfg", the (clear-text) configuration file
of the device that contains, among the other things, also the password for the
"admin" user; thus, escalating to administrative privileges is trivial.
To conclude, please consider that in order to reproduce this issue it is
required to leverage a web browser that supports 128-character long usernames
and passwords (e.g., some versions of IE truncate such a long user/password).
The device manufacturer has released an updated firmware version (v1.07) that
disables the hard-coded accounts.
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