Hard-coded credentials and command-injection vulnerabilities on BigPond 3G21WB

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[ADVISORY INFORMATION]

Title:           Hard-coded credentials and command-injection vulnerabilities

on BigPond 3G21WB

Discovery date:  17/09/2012

Release date:    11/10/2012

Credits:         Roberto Paleari (roberto@greyhats.it, @rpaleari)

[VULNERABILITY INFORMATION]

Class:           Authentication bypass, command-injection

[AFFECTED PRODUCTS]

We confirm the following device models to be affected:

* BigPond 3G21WB

Similar routers are probably vulnerable to these very same issues.

[VULNERABILITY DETAILS]

The firmware running on the affected routers is subject to multiple security

issues that allow an unauthenticated attacker to gain administrative access to

the device and execute arbitrary commands. In the following paragraphs we

describe the details of the vulnerabilities we identified.

a) Hard-coded credentials

A user can authenticate to the web server running on the device using the

credentials "Monitor:bigpond1". These credentials are hard-coded, and cannot

be changed by a normal user.

b) Command-injection vulnerability

The "ping.cgi" web page is subject to a command-injection vulnerability, as

the server-side script does not properly validate user-supplied input.

The following URL exploits this issue, executing the "ls /" command:

http://<device IP address>/ping.cgi?DIA_IPADDRESS=;%20cat%20/etc/passwd

[REMEDIATION]

We are not aware of an updated firmware that corrects the issues described in

this advisory. We suggest users to disable web access on the WAN side.

[DISCLOSURE TIME-LINE]

* 17/09/2012 - Initial vendor contact.

* 18/09/2012 - Vendor replied asking for details.

* 19/09/2012 - The author replied and asked for a technical

contact. Disclosure date set to October 10th, 2012 (3

weeks).

* 19/09/2012 - Vendor replied, providing the phone contact number of the

Technical Support Department.

* 20/09/2012 - The author replied, asking to keep all the communication

through e-mail, in order to keep track of the whole

conversation.

* 24/09/2012 - No response from the vendor. The author re-sent the last

e-mail.

* 04/10/2012 - No response from the vendor. The author re-sent the last

e-mail (again).

* 11/10/2012 - Still no response from the vendor. Disclosure.

[DISCLAIMER]

The author is not responsible for the misuse of the information provided in

this security advisory. The advisory is a service to the professional security

community. There are NO WARRANTIES with regard to this information. Any

application or distribution of this information constitutes acceptance AS IS,

at the user's own risk. This information is subject to change without notice.