Hungarian lab adds storage to D-Link SOHOpeless list

Here's my NAS, do what you please

D-Link users are on the patch-your-stuff-now list again, this time for vulnerabilities in storage devices.

Tests at the Hungarian Search-Lab on DNS-320, DNS-320L, DNS-327L and DNR-326 units using 30-07-2014-dated firmware yielded more than 50 vulnerabilities, including authentication bypasses and something the lab says looks like a backdoor.

The authentication bypass, backdoor, and command injection vulnerabilities, present in all systems, are the most serious, so El Reg will drill into these.

  • Default user authentication bypass – the login CGI script, login_mgr.cgi, directly accesses the file /etc/shadow, which stores passwords including users called “admin”, “root” and “nobody”. The standard UI only gives access to change admin, leaving root and nobody at their defaults unless the user knows they have to disable those accounts. That means root and nobody can be used for authentication bypass with blank passwords.
  • Backdoorcgi_set_wto, a script used during login, doesn't handle its parameters securely. An attacker needs only “to set the Cookie to username=admin and full access to the device was obtained”.
  • Command injection – The check_login CGI script is vulnerable to command injections giving attackers the ability to run arbitrary system commands.

There's a bunch of other vulnerabilities detailed in the full report. These include information leakage, and the ability to upload files to some devices without authentication, to any directory.

The report also notes: “We found a few unsuccessful security workarounds to fix earlier vulnerabilities, which introduced even more serious problems, leading to command injection and the possibility to take full control over the device.”

D-Link has released some, but not all, of the vulnerabilities discovered by the lab. Users should, as always, check and patch their firmware. ®

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