<![CDATA[[SecurityRatty] tag: voip]]> http://securityratty.com/tag/voip Mon, 16 Jun 2008 20:00:00 +0000 iRatty Engine http://blogs.law.harvard.edu/tech/rss <![CDATA[Blue Box #80: VoIPShield vulnerabilities, what is ethical disclosure?, SIP trunking, VoIP security news, new nomadism, and much more...]]> http://securityratty.com/article/f67dc99a7a07715d84135662a2d7276b http://securityratty.com/article/f67dc99a7a07715d84135662a2d7276b

Synopsis:  Blue Box #80: VoIPShield vulnerabilities, what is ethical disclosure?, SIP trunking, VoIP security news, new nomadism, and much more...

Welcome to Blue Box: The VoIP Security Podcast #80, a 44-minute podcast  from Dan York and Jonathan Zar covering VoIP security news, comments and opinions.   

Download the show here (MP3, 20MB) or subscribe to the RSS feed to download the show automatically. 

NOTE: This show was originally recorded on April 17, 2008.

You may also listen to this podcast right now:

Show Content:

Comments, suggestions and feedback are welcome either as replies to this post  or via e-mail to blueboxpodcast@gmail.com.  Audio comments sent as attached MP3 files are definitely welcome and will be played in future shows.  You may also call the listener comment line at either +1-415-830-5439 or via SIP to 'bluebox@voipuser.org' to leave a comment there. 

Thank you for listening and please do let us know what you think of the show.

]]> Tue, 15 Jul 2008 12:22:35 +0000 voip voip security news voip news australia voip news voip security voip security podcast voipsa blog site voipsa voipshield vulnerabilities Blue Box #80: VoIPShield vulnerabilities, what is ethical disclosure?, SIP trunking, VoIP security news, new nomadism, and much more... <![CDATA[Man-in-the-Middle Attacks]]> http://securityratty.com/article/4886f7013362b82e729992218c60dc53 http://securityratty.com/article/4886f7013362b82e729992218c60dc53

The Wall Street Journal reported how this gambit played out in Colombia:

"The plan had a chance of working because, for months, in an operation one army officer likened to a 'broken telephone,' military intelligence had been able to convince Ms. Betancourt's captor, Gerardo Aguilar, a guerrilla known as 'Cesar,' that he was communicating with his top bosses in the guerrillas' seven-man secretariat. Army intelligence convinced top guerrilla leaders that they were talking to Cesar. In reality, both were talking to army intelligence."
This ploy worked because Cesar and his guerrilla bosses didn't know one another well. They didn't recognize one anothers' voices, and didn't have a friendship or shared history that could have tipped them off about the ruse. Man-in-the-middle is defeated by context, and the FARC guerrillas didn't have any. And that's why man-in-the-middle, abbreviated MITM in the computer-security community, is such a problem online: Internet communication is often stripped of any context. There's no way to recognize someone's face. There's no way to recognize someone's voice. When you receive an e-mail purporting to come from a person or organization, you have no idea who actually sent it. When you visit a website, you have no idea if you're really visiting that website. We all like to pretend that we know who we're communicating with -- and for the most part, of course, there isn't any attacker inserting himself into our communications -- but in reality, we don't. And there are lots of hacker tools that exploit this unjustified trust, and implement MITM attacks. Even with context, it's still possible for MITM to fool both sides -- because electronic communications are often intermittent. Imagine that one of the FARC guerrillas became suspicious about who he was talking to. So he asks a question about their shared history as a test: "What did we have for dinner that time last year?" or something like that. On the telephone, the attacker wouldn't be able to answer quickly, so his ruse would be discovered. But e-mail conversation isn't synchronous. The attacker could simply pass that question through to the other end of the communications, and when he got the answer back, he would be able to reply. This is the way MITM attacks work against web-based financial systems. A bank demands authentication from the user: a password, a one-time code from a token or whatever. The attacker sitting in the middle receives the request from the bank and passes it to the user. The user responds to the attacker, who passes that response to the bank. Now the bank assumes it is talking to the legitimate user, and the attacker is free to send transactions directly to the bank. This kind of attack completely bypasses any two-factor authentication mechanisms, and is becoming a more popular identity-theft tactic. There are cryptographic solutions to MITM attacks, and there are secure web protocols that implement them. Many of them require shared secrets, though, making them useful only in situations where people already know and trust one another. The NSA-designed STU-III and STE secure telephones solve the MITM problem by embedding the identity of each phone together with its key. (The NSA creates all keys and is trusted by everyone, so this works.) When two phones talk to each other securely, they exchange keys and display the other phone's identity on a screen. Because the phone is in a secure location, the user now knows who he is talking to, and if the phone displays another organization -- as it would if there were a MITM attack in progress -- he should hang up. Zfone, a secure VoIP system, protects against MITM attacks with a short authentication string. After two Zfone terminals exchange keys, both computers display a four-character string. The users are supposed to manually verify that both strings are the same -- "my screen says 5C19; what does yours say?" -- to ensure that the phones are communicating directly with each other and not with an MITM. The AT&T TSD-3600 worked similarly. This sort of protection is embedded in SSL, although no one uses it. As it is normally used, SSL provides an encrypted communications link to whoever is at the other end: bank and phishing site alike. And the better phishing sites create valid SSL connections, so as to more effectively fool users. But if the user wanted to, he could manually check the SSL certificate to see if it was issued to "National Bank of Trustworthiness" or "Two Guys With a Computer in Nigeria." No one does, though, because you have to both remember and be willing to do the work. (The browsers could make this easier if they wanted to, but they don’t seem to want to.) In the real world, you can easily tell a branch of your bank from a money changer on a street corner. But on the internet, a phishing site can be easily made to look like your bank's legitimate website. Any method of telling the two apart takes work. And that's the first step to fooling you with a MITM attack. Man-in-the-middle isn't new, and it doesn't have to be technological. But the internet makes the attacks easier and more powerful, and that's not going to change anytime soon. This essay originally appeared on Wired.com.
]]> Tue, 15 Jul 2008 02:47:19 +0000 implement mitm attacks implement mitm attacks mitm mitm attack bank bank demands authentication bank assumes attacker inserts Man-in-the-Middle Attacks <![CDATA[Bandwidth calculations for wireless networks supporting VoIP]]> http://securityratty.com/article/1a663308317a28cd02fdbf6e626389e8 http://securityratty.com/article/1a663308317a28cd02fdbf6e626389e8 ]]> Thu, 10 Jul 2008 10:10:28 +0000 wireless enterprise network expert response support simultaneously bandwidth amounts voip calls single user Bandwidth calculations for wireless networks supporting VoIP <![CDATA[How a Classic Man-in-the-Middle Attack Saved Colombian Hostages]]> http://securityratty.com/article/829be68b0dad7d2f6c98b7ac9ac74b63 http://securityratty.com/article/829be68b0dad7d2f6c98b7ac9ac74b63 Last week's dramatic rescue of 15 hostages held by the guerrilla organization FARC was the result of months of intricate deception on the part of the Colombian government. At the center was a classic man-in-the-middle attack.

In a man-in-the-middle attack, the attacker inserts himself between two communicating parties. Both believe they're talking to each other, and the attacker can delete or modify the communications at will. The Wall Street Journal reported how this gambit played out in Colombia.

The plan had a chance of working because, for months, in an operation one army officer likened to a "broken telephone," military intelligence had been able to convince Ms. Betancourt's captor, Gerardo Aguilar, a guerrilla known as "Cesar," that he was communicating with his top bosses in the guerrillas' seven-man secretariat. Army intelligence convinced top guerrilla leaders that they were talking to Cesar. In reality, both were talking to army intelligence.

This ploy worked because Cesar and his guerrilla bosses didn't know each other well. They didn't recognize each others' voices, and didn't have a friendship or shared history that could have tipped them off about the ruse. Man-in-the-middle is defeated by context, and the FARC guerillas didn't have any.

And that's why man-in-the-middle, abbreviated MITM in the computer security community, is such a problem online: Internet communication is often stripped of any context. There's no way to recognize someone's face. There's no way to recognize someone's voice. When you receive an e-mail purporting to come from a person or organization, you have no idea who actually sent it. When you visit a website, you have no idea if you're really visiting that website. We all like to pretend that we know who we're communicating with -- and for the most part, of course, there isn't any attacker inserting himself into our communications -- but in reality, we don't. And there are lots of hacker tools that exploit this unjustified trust, and implement MITM attacks.

Even with context, it's still possible for MITM to fool both sides -- because electronic communications are often intermittent. Imagine that one of the FARC guerillas became suspicious about who he was talking to. So he asks a question about their shared history as a test: "What did we have for dinner that time last year?" or something like that. On the telephone, the attacker wouldn't be able to answer quickly, so his ruse would be discovered. But e-mail conversation isn't synchronous. The attacker could simply pass that question through to the other end of the communications, and when he got the answer back, he would be able to reply.

This is the way MITM attacks work against web-based financial systems. A bank demands authentication from the user: a password, a one-time code from a token or whatever. The attacker sitting in the middle receives the request from the bank and passes it to the user. The user responds to the attacker, who passes that response to the bank. Now the bank assumes it is talking to the legitimate user, and the attacker is free to send transactions directly to the bank. This kind of attack completely bypasses any two-factor authentication mechanisms, and is becoming a more popular identity theft tactic.

There are cryptographic solutions to MITM attacks, and there are secure web protocols that implement them. Many of them require shared secrets, though, making them only useful in situations where people already know and trust each other.

The NSA-designed STU-III and STE secure telephones solve the MITM problem by embedding the identity of each phone together with its key. (The NSA creates all keys and is trusted by everyone, so this works.) When two phones talk to each other securely, they exchange keys and display the other phone's identity on a screen. Because the phone is in a secure location, the user now knows who he is talking to, and if the phone displays another organization -- as it would if there were a MITM attack in progress -- he should hang up.

Zfone, a secure VoIP system, protects against MITM attacks with a short authentication string. After two Zfone terminals exchange keys, both computers display a four-character string. The users are supposed to manually verify that both strings are the same -- "my screen says 5C19; what does yours say?" -- to ensure that the phones are communicating directly with each other and not with an MITM. The AT&T TSD-3600 worked similarly.

This sort of protection is embedded in SSL, although no one uses it. As it is normally used, SSL provides an encrypted communications link to whoever is at the other end: bank and phishing site, alike. And the better phishing sites create valid SSL connections, so as to more effectively fool users. But if the user wanted to, he could manually check the SSL certificate to see if it was issued to "National Bank of Trustworthiness" or "Two Guys With a Computer in Nigeria."

No one does, though, because you both have to remember and be willing to do the work. (The browsers could make this easier if they wanted to, but they don’t seem to want to.) In the real world, you can easily tell a branch of your bank from a money changer on a streetcorner. But on the internet, a phishing site can be easily made to look like your bank's legitimate website. Any method of telling the two apart takes work. And that's the first step to fooling you with a MITM attack.

Man-in-the-middle isn't new, and it doesn't have to be technological. But the internet makes the attacks easier and more powerful, and that's not going to change anytime soon.

---

Bruce Schneier is chief security technology officer of BT, and author of Beyond Fear: Thinking Sensibly About Security in an Uncertain World.


]]> Wed, 09 Jul 2008 21:00:00 +0000 implement mitm attacks implement mitm attacks mitm attack mitm attack bank bank demands authentication bank assumes How a Classic Man-in-the-Middle Attack Saved Colombian Hostages <![CDATA[Avaya, Cisco and Nortel face VoIP vulnerabilities]]> http://securityratty.com/article/4b72816b4ab5098febf61ab4b095ad5f http://securityratty.com/article/4b72816b4ab5098febf61ab4b095ad5f

]]> Wed, 25 Jun 2008 09:00:00 +0000 affect voice servers voip pbxes softphone software issues laptops runs patches desktops Avaya, Cisco and Nortel face VoIP vulnerabilities <![CDATA[T-Mobile Takes Home Line Service National]]> http://securityratty.com/article/f21fde7220aa4829afc10dd0ff2bc8d3 http://securityratty.com/article/f21fde7220aa4829afc10dd0ff2bc8d3 T-Mobile launches nationwide July 2nd with its home-line replacement service--or is it a cell plan extension service? I link here to Seattle Times's columnist Brier Dudley's take on @Home, T-Mobile's $10 per month unlimited domestic home calling service that leverages customers' existing cell service and broadband connection. The service launched in the Seattle area several months ago, and is expanding nationally, and Dudley interviews T-Mobile's boss Robert Dotson for the story. Dotson says T-Mobile doesn't see @Home as a way to get folks to necessarily cut their landline cord, but rather to extend the function of a cell phone inside the house, even if you're using cordless not cellular devices.

The service uses a router that accepts SIM cards for authentication, but the backhaul is pure VoIP over Internet. Regular POTS (plain old telephone service) phones can be plugged into the router. The router is also compatible with HotSpot@Home (an additional $10/month), which allows unlimited domestic calling over Wi-Fi using special handsets from T-Mobile; there are now 8 handset models available. Customers have to have at least a $40 single-line or $50 family plan service to add either @Home or HotSpot@Home.

Probably the key remaining advantage for Vonage and other Internet telephony services that typically charge $20 to $30 per month for unlimited calling is that they include unlimited calls to any number in Canada or the U.S., not just the U.S., as well as unmetered calls to landlines in dozens of other countries in Europe as well as Australia. For those who regularly call outside the U.S., the @Home service would quickly become ridiculously expensive for its international tolls.

]]> Wed, 25 Jun 2008 06:33:49 +0000 service family plan service home service home cell service t-mobile telephone service home-line replacement service domestic home T-Mobile Takes Home Line Service National <![CDATA[Eavesdropping on Encrypted Compressed Voice]]> http://securityratty.com/article/01d3679a43ebdd7cdab4158981f0f4fb http://securityratty.com/article/01d3679a43ebdd7cdab4158981f0f4fb Traffic analysis works even through the encryption:

The new compression technique, called variable bitrate compression produces different size packets of data for different sounds.

That happens because the sampling rate is kept high for long complex sounds like "ow", but cut down for simple consonants like "c". This variable method saves on bandwidth, while maintaining sound quality.

VoIP streams are encrypted to prevent eavesdropping. However, a team from John Hopkins University in Baltimore, Maryland, US, has shown that simply measuring the size of packets without decoding them can identify whole words and phrases with a high rate of accuracy.

The technique isn't good enough to decode entire conversations, but it's pretty impressive.

]]> Thu, 19 Jun 2008 02:27:13 +0000 variable variable method saves compression technique technique john hopkins university decode entire conversations complex sounds sounds packets Eavesdropping on Encrypted Compressed Voice <![CDATA[Security Briefing: June 18th]]> http://securityratty.com/article/6ecf8ade3790e74d26a7082c7e2eb3c0 http://securityratty.com/article/6ecf8ade3790e74d26a7082c7e2eb3c0
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And now, the news…

  1. Most Attractive Targets: SaaS | GNUCITIZEN
  2. Microsoft patch resolves patching blockage | Heise
  3. Instant trojan to worm toolkit sighted | The Register
  4. PGP Source Code Book on eBay | Infosecurity dot us
  5. Why most WAFs do not block | Jeremiah Grossman
  6. VoIP providers to get full 911 access with bill’s passage | Ars Technica
  7. Being a Government Security CISO: Life in the Fishbowl | Bloginfosec
  8. Current cyber-security defences ‘ineffective’ (deduct 10 points for use of “cyber”) | vnunet

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]]> Wed, 18 Jun 2008 09:47:09 +0000 security news news government security ciso microsoft patch resolves bills passage instant trojan jeremiah grossman ars technica attractive targets Security Briefing: June 18th <![CDATA[Senate passes VoIP emergency-dialing bill]]> http://securityratty.com/article/47b074523463abb30ee3ad2f05e5cfd0 http://securityratty.com/article/47b074523463abb30ee3ad2f05e5cfd0 Mon, 16 Jun 2008 20:00:00 +0000 voip providers requires operators networks legislation connect Senate passes VoIP emergency-dialing bill <![CDATA[Compression lets attackers tap VoIP calls]]> http://securityratty.com/article/10b6a4fc73675f001a9c5f007e4803fe http://securityratty.com/article/10b6a4fc73675f001a9c5f007e4803fe Mon, 16 Jun 2008 20:00:00 +0000 johns hopkins university common compression technique recent research susceptible Compression lets attackers tap VoIP calls