SIP Security 5

Question 1

What is the primary security function of the 'opaque' parameter in SIP Digest Authentication?

Accepted Answer

It allows the server to pass state information that the client must return unchanged

Answer

It specifies the encryption algorithm for the session key

Answer

It provides a secondary nonce for enhanced replay protection

Answer

It identifies the authentication realm to the client

Question 2

Which attack exploits SIP's UDP transport by spoofing the source IP address of SIP messages?

Accepted Answer

SIP source address spoofing to bypass IP-based access control

Answer

SIP flooding from a botnet

Answer

DNS-based SIP routing attack

Answer

SDP manipulation via MITM

Question 3

In a SIP 'call hijacking via re-INVITE' attack, what is the attacker's goal?

Accepted Answer

Redirect the media stream to an attacker-controlled endpoint by modifying SDP in a re-INVITE

Answer

Terminate the call by sending a spoofed BYE

Answer

Steal authentication credentials from the re-INVITE transaction

Answer

Prevent codec renegotiation to degrade call quality

Question 4

Which IETF standard defines the use of DTLS-SRTP for securing media in WebRTC-based SIP scenarios?

Accepted Answer

RFC 5764

Answer

RFC 4568

Answer

RFC 3711

Answer

RFC 6347

Question 5

What is 'SIP vishing' and how does it exploit SIP infrastructure?

Accepted Answer

Voice phishing calls made over SIP with spoofed caller ID to deceive victims

Answer

Compromising SIP credentials via a phishing website

Answer

Intercepting VoIP calls to harvest sensitive spoken information

Answer

Using SIP NOTIFY to push malicious content to IP phones

Question 6

Which SIP security practice involves stripping 'Via' headers at the border to prevent topology disclosure?

Accepted Answer

Topology hiding via Session Border Controller (SBC)

Answer

SIP header normalization at the proxy

Answer

TLS certificate pinning at the border

Answer

SIP firewall header filtering

Question 7

What does the SIP 'Require' header with the value 'sec-agree' enforce according to RFC 3329?

Accepted Answer

Both endpoints must negotiate and agree on a security mechanism before proceeding

Answer

The server must use TLS for all subsequent requests in the dialog

Answer

The client must provide valid credentials before the session is established

Answer

Both parties must support SRTP for the media stream