SIP Security 3

Question 1

In SIP, what does 'SPIT' stand for and what threat does it represent?

Accepted Answer

Spam over Internet Telephony — unsolicited bulk voice calls

Answer

SIP Protocol Interception Technique — call eavesdropping

Answer

Session Protocol Integrity Testing — security auditing

Answer

Secure Peer Identity Token — caller verification

Question 2

Which SIP header prevents a response from being replayed by an attacker to a different transaction?

Accepted Answer

CSeq

Answer

Via

Answer

Call-ID

Answer

Contact

Question 3

What is a 'SIP proxy poisoning' attack?

Accepted Answer

Injecting false routing information to redirect SIP traffic through a malicious proxy

Answer

Overloading a SIP proxy with authentication requests

Answer

Extracting credentials from a SIP proxy's configuration

Answer

Modifying SDP offers at a proxy to insert attacker media endpoints

Question 4

Which field in the SIP Digest Authentication challenge is used to prevent cross-realm credential reuse?

Accepted Answer

realm

Answer

nonce

Answer

opaque

Answer

algorithm

Question 5

TLS in SIP provides security for traffic between which entities?

Accepted Answer

Adjacent SIP hops (hop-by-hop)

Answer

Caller and callee end-to-end

Answer

Only between UAC and the first proxy

Answer

Only between the last proxy and UAS

Question 6

What is 'toll fraud' in the context of SIP security?

Accepted Answer

Unauthorized use of a SIP system to make expensive calls at the victim's expense

Answer

Fraudulent billing by a SIP service provider

Answer

Intercepting premium-rate call content for re-sale

Answer

Forging caller ID on international calls

Question 7

Which SIP response code indicates that the server has rejected a request because the credentials provided have expired?

Accepted Answer

401 Unauthorized (with stale=true in WWW-Authenticate)

Answer

403 Forbidden

Answer

407 Proxy Authentication Required

Answer

491 Request Pending