<![CDATA[[SecurityRatty] tag: zfone]]> http://securityratty.com/tag/zfone Wed, 17 Oct 2007 09:40:41 +0000 iRatty Engine http://blogs.law.harvard.edu/tech/rss <![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[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[Blue Box #79: Asterisk vulnerabilities, VoiceCon/VON coverage, eavesdropping, FBI, ZFone, P2P, VoIP security news and more]]> http://securityratty.com/article/12a646d6f75cd20c5bdf249647b13de5 http://securityratty.com/article/12a646d6f75cd20c5bdf249647b13de5

Synopsis:  Blue Box #79: Asterisk vulnerabilities, VoiceCon/VON coverage, eavesdropping, FBI, ZFone, P2P, VoIP security news and more

Welcome to Blue Box: The VoIP Security Podcast #78, a 32-minute podcast  from Dan York and Jonathan Zar covering VoIP security news, comments and opinions.   

Download the show here (MP3, 15MB) or subscribe to the RSS feed to download the show automatically. 

NOTE: This show was originally recorded on March 27, 2008. Yes, that was over two months ago... we know...

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.

]]> Mon, 09 Jun 2008 12:30:57 +0000 voip voip security news voip monitor security voip news asterisk vulnerabilities voip security podcast blue box podcast Blue Box #79: Asterisk vulnerabilities, VoiceCon/VON coverage, eavesdropping, FBI, ZFone, P2P, VoIP security news and more <![CDATA[Blue Box #79: Asterisk vulnerabilities, VoiceCon/VON coverage, eavesdropping, FBI, ZFone, P2P, VoIP security news and more]]> http://securityratty.com/article/6ff472aef8df8c39ce9d47bf4fe36d51 http://securityratty.com/article/6ff472aef8df8c39ce9d47bf4fe36d51

Synopsis:  Blue Box #79: Asterisk vulnerabilities, VoiceCon/VON coverage, eavesdropping, FBI, ZFone, P2P, VoIP security news and more

Welcome to Blue Box: The VoIP Security Podcast #78, a 32-minute podcast  from Dan York and Jonathan Zar covering VoIP security news, comments and opinions.   

Download the show here (MP3, 15MB) or subscribe to the RSS feed to download the show automatically. 

NOTE: This show was originally recorded on March 27, 2008. Yes, that was over two months ago... we know...

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.

]]> Mon, 09 Jun 2008 11:30:58 +0000 voip voip security news voip monitor security voip news asterisk vulnerabilities voip security podcast blue box podcast Blue Box #79: Asterisk vulnerabilities, VoiceCon/VON coverage, eavesdropping, FBI, ZFone, P2P, VoIP security news and more <![CDATA[Encrypting VoIP Traffic With Zfone To Protect Against Wiretapping]]> http://securityratty.com/article/92c70ade0197a92798ae41321221585a http://securityratty.com/article/92c70ade0197a92798ae41321221585a New Video:Encrypting VoIP Traffic With Zfone To Protect Against Wiretapping
Some people worry about the easy with which their voice communications may be spied upon. Laws like CALEA have made this simpler in some ways, and with roaming wiretaps even those not under direct investigation may lose their privacy. Phil Zimmermann , creator of PGP, has come up with a project called Zfone which aims to do for VoIP what PGP did for email. Thanks to DOSMan for his help with this video.]]> Sun, 27 Jan 2008 22:02:30 +0000 voip traffic voip zfone voice communications people worry protect pgp phil zimmermann video Encrypting VoIP Traffic With Zfone To Protect Against Wiretapping <![CDATA[Encrypting VoIP Traffic With Zfone To Protect Against Wiretapping]]> http://securityratty.com/article/c48be9aa68f15e9dee630d61a6db009c http://securityratty.com/article/c48be9aa68f15e9dee630d61a6db009c New Video:Encrypting VoIP Traffic With Zfone To Protect Against Wiretapping
Some people worry about the easy with which their voice communications may be spied upon. Laws like CALEA have made this simpler in some ways, and with roaming wiretaps even those not under direct investigation may lose their privacy. Phil Zimmermann , creator of PGP, has come up with a project called Zfone which aims to do for VoIP what PGP did for email. Thanks to DOSMan for his help with this video.

]]> Sun, 27 Jan 2008 22:02:30 +0000 voip traffic voip zfone voice communications people worry protect pgp phil zimmermann video Encrypting VoIP Traffic With Zfone To Protect Against Wiretapping <![CDATA[Encrypting VoIP Traffic With Zfone To Protect Against Wiretapping]]> http://securityratty.com/article/3fea1666e38085ffa64e1c13ca2a0414 http://securityratty.com/article/3fea1666e38085ffa64e1c13ca2a0414 New Video:Encrypting VoIP Traffic With Zfone To Protect Against Wiretapping
Some people worry about the easy with which their voice communications may be spied upon. Laws like CALEA have made this simpler in some ways, and with roaming wiretaps even those not under direct investigation may lose their privacy. Phil Zimmermann , creator of PGP, has come up with a project called Zfone which aims to do for VoIP what PGP did for email. Thanks to DOSMan for his help with this video.]]> Sun, 27 Jan 2008 22:02:30 +0000 voip traffic voip zfone voice communications people worry protect pgp phil zimmermann video Encrypting VoIP Traffic With Zfone To Protect Against Wiretapping <![CDATA[Blue Box SE#021: Interview with ZFone and ZRTP creator Phil Zimmermann by Brenno de Winter]]> http://securityratty.com/article/6ff42a64e65b1bb8d734a816677026e6 http://securityratty.com/article/6ff42a64e65b1bb8d734a816677026e6

Synopsis: Interview with ZFone and ZRTP creator Phil Zimmermann by Brenno de Winter.

Welcome to Blue Box: The VoIP Security Podcast Special Edition #21, a 44-minute interview between Phil Zimmermann and Brenno de Winter in August 2007.

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

You may also listen to this podcast right now:

Show Content:

Brenno de Winter produces a Dutch podcast about information technology news called "ICT Roddels" (http://ictroddels.nl/) and back in early August he sat down with ZFone and ZRTP creator Phil Zimmermann to discuss (in English) what ZFone and ZRTP are all about. Brenno released the interview on his show and then offered it to us to run as a Blue Box show. In the 40-minute interview, Brenno and Phil spend the first 20 or so minutes talking about ZFone, ZRTP and VoIP security and then spend the remainder of the show talking about security in general, Phil's background and other topics.

While we have interviewed Phil in the past ourselves, it's been about a year since we last spoke with him and so we thought this might be an interesting update for you to hear. We thank Brenno for making the interview available to us.

I also have to say a word of thanks to long-time contributor Martyn Davies who stepped in at the last moment to provide the intro/outro to this interview. I unfortunately lost my voice after a presentation yesterday (bad news for a podcaster!) and Jonathan is currently traveling - and our goal this year is to make sure we get shows out on Wednesdays.

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 +1-206-350-7280 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.

]]> Sat, 27 Oct 2007 10:33:04 +0000 interview brenno phil phil zimmermann zfone 40-minute interview winter blue box 44-minute interview Blue Box SE#021: Interview with ZFone and ZRTP creator Phil Zimmermann by Brenno de Winter <![CDATA[Blue Box SE#021: Interview with ZFone and ZRTP creator Phil Zimmermann by Brenno de Winter]]> http://securityratty.com/article/d8d1e1f6d71387dbbdf712d013317cd1 http://securityratty.com/article/d8d1e1f6d71387dbbdf712d013317cd1

Synopsis: Interview with ZFone and ZRTP creator Phil Zimmermann by Brenno de Winter.

Welcome to Blue Box: The VoIP Security Podcast Special Edition #21, a 44-minute interview between Phil Zimmermann and Brenno de Winter in August 2007.

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

You may also listen to this podcast right now:

Show Content:

Brenno de Winter produces a Dutch podcast about information technology news called "ICT Roddels" (http://ictroddels.nl/) and back in early August he sat down with ZFone and ZRTP creator Phil Zimmermann to discuss (in English) what ZFone and ZRTP are all about. Brenno released the interview on his show and then offered it to us to run as a Blue Box show. In the 40-minute interview, Brenno and Phil spend the first 20 or so minutes talking about ZFone, ZRTP and VoIP security and then spend the remainder of the show talking about security in general, Phil's background and other topics.

While we have interviewed Phil in the past ourselves, it's been about a year since we last spoke with him and so we thought this might be an interesting update for you to hear. We thank Brenno for making the interview available to us.

I also have to say a word of thanks to long-time contributor Martyn Davies who stepped in at the last moment to provide the intro/outro to this interview. I unfortunately lost my voice after a presentation yesterday (bad news for a podcaster!) and Jonathan is currently traveling - and our goal this year is to make sure we get shows out on Wednesdays.

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 +1-206-350-7280 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.

]]> Wed, 17 Oct 2007 09:40:41 +0000 interview brenno phil phil zimmermann zfone 40-minute interview winter blue box 44-minute interview Blue Box SE#021: Interview with ZFone and ZRTP creator Phil Zimmermann by Brenno de Winter