October Touchdown Task: Phone System Review

This month’s Touchdown Task is to take an hour and give your phone system security a quick review. PBX hacking, toll fraud and VoIP attacks remain fairly common and many organizations don’t often visit the security of their phone systems. Thus, a quick review might find some really interesting things and go a long way to avoiding waste, fraud and abuse.

If you have a traditional PBX/analog phone system, here are some ideas for you to check out.

If you have a VoIP-based system, here are some checks to consider. (Note that this is a STIG in a  zip file). 

Generally speaking, you want to check passwords on voice mail boxes, give a look over to make sure that the phone system has some general logging/alerting capability and that it is turned on. Pay attention to out going dialing rules and test a few to make sure arbitrary calls can’t be made remotely. On the personnel side, make sure someone is actively monitoring the phone system, auditing the bill against “normal” and adding/deleting entries in the system properly.

Give the phone system a bit of your time. You never know what you might learn, and you might avoid tens to hundreds of thousands of dollars in fraud and abuse.

Thanks for reading and I hope you are enjoying the season! 

Don’t Forget About VoIP Exposures and PBX Hacking







I was browsing my usual data alerts for the day and ran into this set of data. It motivated me to write a quick blog post to remind folks that VoIP scans and probes are still going on out there in the wild.

These days, with all of the attention to mass compromises, infected web sites and stolen credit card data, voice systems can sometimes slip out of sight.

VoIP compromises and intrusions remain a threat. There are now a variety of tools, exploits and frameworks built for attacking VoIP installations and they are a target for both automated tools and manual hacking. Access to VoIP systems can provide a great platform for intelligence, recon, industrial espionage and traditional toll fraud.
While VoIP might be the state of the art for phone systems today, there are still plenty of traditional PBX, auto-attendant and dial-up voicemail systems around too. Now might be a good time to review when those systems were last reviewed, audited or pen-tested. Traditional toll fraud is still painful to manage and recover from, so it’s probably worth spending a few cycles on reviewing these devices and their security postures. 
Let us know if your organization could use assistance with these items or with hardening voice systems, implementing detection techniques for them or otherwise increasing voice system security.

VoIPER – A VoIP Fuzzing Tool

VoIPER, a VoIP fuzzing framework, has been released. This tool includes a suite built on the Sulley fuzzing framework and a SIP torturer. The fuzzer currently incorporates tests for SIP INVITE, SIP ACK, SIP CANCEL, SIP request structure, and SPD over SIP. VoIPER, and tools like it, are likely to increase the likely hood that additional SIP vulnerabilities will be found. Proper architecture and configuration surrounding a SIP implementation is likely to reduce the potential for compromise in almost all scenarios.

SWF Whitepaper and VoIP Vulns

There is a guide available from Adobe on creating secure Flash applications. In the wake of the mid December Adobe Shockwave Flash vulnerabilities, Adobe has released a white paper on “Creating more secure SWF web applications”. This, combined with flash data validation libraries available from Google, allow for a complete solution to any potential vulnerabilities. Developers of Flash animations/movies/applications should take the time to read over this document and see where they could use the data validation libraries within their environment. Security teams should be testing all of their environments Flash applications for any vulnerabilities and coordinate to get these resolved. From what I’ve read, when Adobe makes the second update for these issues available early 2008, the issues will not be completely resolved in already developed Flash applications.

Here’s a link to the article http://www.adobe.com/devnet/flashplayer/articles/secure_swf_apps.html and the validation libraries http://code.google.com/p/flash-validators/

Also, it appears a few SIP vendors have had vulnerabilities reported in them today. Avaya is affected by two issues, one in pam and the other in OpenSSH. The issue in pam could allow for the disclosure of sensitive data, or allow the injection of characters into log entries. The issue with OpenSSH could allow arbitrary code execution (race condition) and the discovery of valid usernames. Here’s the original Avaya advisories: http://support.avaya.com/elmodocs2/security/ASA-2007-526.htm and http://support.avaya.com/elmodocs2/security/ASA-2007-527.htm

Asterisk is vulnerable to a Denial of Service when handling the “BYE/Also” transfer method. Exploitation requires that a dialog already be established between the two parties. Asterisk versions prior to 1.4.17 are vulnerable. The issue is fixed in version 1.4.17.

Avaya Products Multiple Vulnerabilities

Avaya has released information on multiple vulnerabilities within their products. The first issue is an error in certain OpenSSL functions.  A certain function can be exploited to cause a buffer overlow and a weakness in the RSA implementation can be exploited to reveal the private keys. The following products are affected:

  • Avaya Communication Manager (CM 3.0)
  • Avaya EMMC (1.017, 1.021)
  • Avaya CCS/SES (3.1 and earlier)
  • Avaya AES (AES 3.1.4 and earlier)

The next set of issues lies in the PCRE libraries. When parsing certain regular expressions an integer overflow can occur and result in a denial of service or potentially compromise an application using the library.  Additionally, an error processing multiple unspecified character classes can be exploited to cause insufficient memory allocation.

The following versions are affected:

  • Avaya Communication Manager (CM 3.1, CM 4.x)
  • Avaya Intuity AUDIX LX (IALX 2.0)
  • Avaya Messaging Storage Server (MSS 3.x)
  • Avaya Message Networking (MN 3.1)
  • Avaya CCS/SES (3.1.1, 3.1.2, 4.0)
  • Avaya AES (AES 4.0.1)