Monday, 28 May 2018

Abusing IVR Systems - Legacy Telecom [CVE-2018-11518]

Hi Internet,

CVE-2018-11518, (Everything old, is new again.)
A vulnerability allows a phreaking attack on HCL legacy IVR systems that do not use VoIP. These IVR systems rely on various frequencies of audio signals; based on the frequency, certain commands and functions are processed. Since these frequencies are accepted within a phone call, an attacker can record these frequencies and use them to activate services or to get sensitive information.

PS: This is a request-forgery issue when the required series of DTMF signals for a service activation is predictable (e.g., the IVR system does not speak a nonce to the caller). In this case, the IVR system accepts an activation request from a less-secure channel (any loudspeaker in the caller's physical environment) without verifying that the request was intended (it matches a nonce sent over a more-secure channel to the caller's earpiece).

Video PoC: Phreak Attack


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