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Man in The Middle. Christopher Avilla. What is a MiTM attack?. Mallory in the Middle. Alice "Hi Bob, it's Alice. Give me your key" --> Mallory Bob Alice Mallory "Hi Bob, it's Alice. Give me your key" --> Bob Alice Mallory <-- [ Bob's_key ] Bob Alice <-- [ Mallory's_key ] Mallory Bob
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Man in The Middle Christopher Avilla
Mallory in the Middle • Alice"Hi Bob, it's Alice. Give me your key"--> MalloryBob • AliceMallory"Hi Bob, it's Alice. Give me your key"--> Bob • AliceMallory <--[Bob's_key]Bob • Alice <--[Mallory's_key]MalloryBob • Alice"Meet me at the bus stop!"[encrypted with Mallory's key]--> MalloryBob • AliceMallory"Do not meet me!"[encrypted with Bob's key]--> Bob
GSM Network MiTM • International Mobile Subscriber Identity (IMSI) • GSM equivalent to a username • Universal Software Radio Peripheral (USRP) • http://revision3.com/hak5/shmoocon2010
Functional Weaknesses of System • Ability for base station to tell hand set that it will not get cipher • Plain text between phone and SIM card
GSM Hand Shake • Secret Key in SIM Card • Base station sends 128 bit Random number • SIM Card concats 128 with Secret Key • Hashes the result and splits in two • Half is sent back to base station • Half is used for cypher A5 • A53 is 3G encryption
OpenBTS • Hooks in to Asterisk (VoIP) • SIP proxy with voice changer • Target specific phone number and route all calls to 911 • Sniff all SIP packets and replay conversations http://openbts.sourceforge.net/
Don’t be a Victim • Third Party Applications – AntiARP or XArp • http://www.raymond.cc/blog/archives/2009/08/07/protect-your-computer-against-arp-poison-attack-netcut/ • Look at your ARP table by ARP/a or ARP –a • Use static ARP tables • A fine tuned IDS will alert you when you’ve fallen • GSM phone should alert you when non-encrypted
Resources • http://en.wikipedia.org/wiki/Universal_Software_Radio_Peripheral • http://en.wikipedia.org/wiki/ARP_spoofing • http://www.irongeek.com/ • http://www.monkey.org/~dugsong/dsniff/faq.html • http://openmaniak.com/ettercap_filter.php • http://www.shmoocon.org/presentations-all.html • http://openbts.sourceforge.net/ • http://revision3.com/hak5/pineapples • http://revision3.com/hak5/shmoocon2010