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Potential SIP REGISTER Brute Force

Identifies repeated SIP REGISTER authentication rejection responses for one or more extensions from a client to a VoIP server within five minutes. The rule distinguishes repeated failures from the single 401 or 407…

Description

Identifies repeated SIP REGISTER authentication rejection responses for one or more extensions from a client to a VoIP server within five minutes. The rule distinguishes repeated failures from the single 401 or 407 challenge expected in a normal digest-authentication flow. Attackers brute-force extension credentials to register rogue endpoints for toll fraud, call interception, or registration hijacking.

Detection logic

Its licence does not clear it for publishing here

Sunturai publishes a detection's own text where the licence it arrived under has been reviewed and permits it, and Elastic License 2.0 has not. The query as its source wrote it, its canonical form and the hash that pins this revision are in the workspace record.

Detection requirements

Platform
ContainersESXiIaaSIdentity ProviderLinuxmacOSNetwork DevicesOffice SuiteSaaSWindows

The rule states no platform. This is derived from the ATT&CK technique it maps to.

Known benign triggers

  • Misconfigured phones, expired credentials, or provisioning errors can generate repeated REGISTER failures from a single device. Validate the client, affected extensions, and registration state before escalating.

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