[ADVISORY INFORMATION] Title: Sitecom WLM-3500 backdoor accounts Discovery date: 24/03/2013 Release date: 16/04/2013 Credits: Roberto Paleari (email@example.com, @rpaleari) Advisory URL: http://blog.emaze.net/2013/04/sitecom-wlm-3500-backdoor-accounts.html
[VULNERABILITY INFORMATION] Class: Authentication bypass
[AFFECTED PRODUCTS] We confirm the presence of the security vulnerability on the following products/firmware versions:
Other device models and firmware versions are probably also vulnerable, but they were not checked.
[VULNERABILITY DETAILS] 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:
username: qwertyuiopqwertyuiopqwertyuiopqwertyuiopqwertyuiopqwertyuiopqwertyuiopqwertyuiopqwertyuiopqwertyuiopqwertyuiopqwertyuiopqwertyui password: 12345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678
username: user3 password: 12345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678
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).
[REMEDIATION] The device manufacturer has released an updated firmware version (v1.07) that disables the hard-coded accounts.
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