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Collaboration, Voice & AV · Intermediate

SIP Scanning

Automated probing of the internet or a network for SIP devices and extensions, often as reconnaissance for toll fraud.

Definition

Tools such as SIPVicious send OPTIONS or REGISTER requests to discover SIP servers, enumerate valid extensions from differing responses and brute-force passwords. Exposed gateways and PBXs receive constant scanning traffic. Defenses include not exposing SIP directly to the internet, using SBCs with access lists and rate limits, consistent error responses and intrusion prevention signatures.

Example

A CUBE log shows hundreds of OPTIONS requests from an unknown host with the user agent friendly-scanner.

Exam tip

Reduce exposure with SBCs, ACLs, the CUBE trusted list and TLS.

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