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AUSCERT External Security Bulletin Redistribution
Cisco 1800 Series ISR ISDN Basic Rate Interface Denial of
29 August 2014
AusCERT Security Bulletin Summary
Product: Cisco 1800 Series ISR
Publisher: Cisco Systems
Operating System: Cisco IOS
Impact/Access: Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2014-3347
Comment: Mitigation of this vulnerability by restricting knowledge of the
ISDN number for affected systems connected to public switched
networks is recommended.
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Cisco Security Notice
Cisco 1800 Series ISR ISDN Basic Rate Interface Denial of Service
CVE ID: CVE-2014-3347
Release Date: 2014 August 27 18:40 UTC (GMT)
Last Updated: 2014 August 28 15:58 UTC (GMT)
Cisco 1800 Series Integrated Services Routers (ISR) contain a vulnerability in
the hardware entropy collection module when the Integrated Services Digital
Network (ISDN) Basic Rate Interface (BRI) is configured and connected to a
public switched network. This could allow an attacker with knowledge of the
ISDN phone number of the affected device to trigger a denial of service (DoS)
The vulnerability is due to an interrupt timer collision that causes the
hardware encryption module to enter a corrupted state, causing the device to
become unresponsive. An attacker would need to perform the attack exactly when
the device polls the hardware encryption module to perform entropy collection.
The affected devices have reached the End of Software Maintenance milestone.
Fixed software will not be released.
Product More Information CVSS
IOS CSCul77897 5.4/4.9
What Is a Cisco Security Notice?
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Security Notices to inform customers of low- to mid-level severity security
issues involving Cisco products.
Customers who wish to upgrade to a software version that includes fixes for
these issues should contact their normal support channels. Free software
updates will not be provided for issues that are disclosed through a Cisco
For additional information about Cisco PSIRT publications, see the Cisco
Security Vulnerability Policy at
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products, customers should consult their service providers or support
organizations to ensure that any applied workaround or fix is the most
appropriate in the intended network before it is deployed.
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