cisco-sa-20190925-isdn-data-leak: Cisco IOS XE Software ISDN Data Leak Vulnerability
First published: Wed Sep 25 2019(Updated: )
A vulnerability in the Dialer interface feature for ISDN connections in Cisco IOS XE Software for Cisco 4000 Series Integrated Services Routers (ISRs) could allow an unauthenticated, adjacent attacker to pass IPv4 traffic through an ISDN channel prior to successful PPP authentication. The vulnerability is due to insufficient validation of the state of the PPP IP Control Protocol (IPCP). An attacker could exploit this vulnerability by making an ISDN call to an affected device and sending traffic through the ISDN channel prior to successful PPP authentication. Alternatively, an unauthenticated, remote attacker could exploit this vulnerability by sending traffic through an affected device that is configured to exit via an ISDN connection for which both the Dialer interface and the Basic Rate Interface (BRI) have been configured, but the Challenge Handshake Authentication Protocol (CHAP) password for PPP does not match the remote end. A successful exploit could allow the attacker to pass IPv4 traffic through an unauthenticated ISDN connection for a few seconds, from initial ISDN call setup until PPP authentication fails. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. This advisory is available at the following link: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190925-isdn-data-leak
Credit: This vulnerability was found during the resolution a Cisco TAC support case
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Cisco IOS XE Software | ||
| Cisco 4000 Series Integrated Services Routers |
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Reference Links
Frequently Asked Questions
What is the severity of cisco-sa-20190925-isdn-data-leak?
The severity of cisco-sa-20190925-isdn-data-leak is rated as high.
How do I fix cisco-sa-20190925-isdn-data-leak?
To fix cisco-sa-20190925-isdn-data-leak, upgrade to a fixed version of Cisco IOS XE Software as advised by Cisco.
What systems are affected by cisco-sa-20190925-isdn-data-leak?
Cisco 4000 Series Integrated Services Routers running Cisco IOS XE Software are affected by cisco-sa-20190925-isdn-data-leak.
Can an attacker exploit cisco-sa-20190925-isdn-data-leak remotely?
No, an attacker must be adjacent to the affected device to exploit cisco-sa-20190925-isdn-data-leak.
What type of attack is possible with cisco-sa-20190925-isdn-data-leak?
cisco-sa-20190925-isdn-data-leak allows an attacker to pass IPv4 traffic through an ISDN channel before PPP authentication.
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