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Juniper Networks NetScreen firewall contains a DoS vulnerability in the SSHv1 service

Vulnerability Note VU#749870

Original Release Date: 2004-08-13 | Last Revised: 2004-08-13


A vulnerability in the SSHv1 service of NetScreen firewalls could allow an attacker to cause a denial-of-service condition.


Juniper Networks NetScreen firewall products include a Secure Shell version 1 (SSHv1) implementation called Secure Command Shell (SCS). The SSHv1 service contains a remotely exploitable denial-of-service vulnerability.

According to the Juniper Networks Security Advisory:
A malicious person who can connect to the SSHv1 service on a Juniper Networks Netscreen firewall can crash the device before having to authenticate. Upon execution of the attack, the firewall will reboot or hang, which will prevent traffic to flow through the device.


A remote, unauthenticated attacker could cause a denial-of-service condition.



Please refer to the "Recommended Actions" section of the Juniper Networks Advisory for more information on upgrading.

Disable SSHv1

Disable SSHv1 and manage the affected device using another method, such as HTTPS.

Restrict Access

Block or restrict access to the SSHv1 service from untrusted networks, such as the Internet. Juniper Networks also recommends enabling IP Spoof protection to provide additional security.

Vendor Information


Juniper Networks Affected

Updated:  August 13, 2004



Vendor Statement

We have not received a statement from the vendor.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.


Please refer to Juniper Networks NetScreen Security Advisory 59147.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

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This vulnerability was reported by Juniper Networks. In turn, Juniper Networks credits Mark Ellzey Thomas of NaviSite for discovering this vulnerability.

This document was written by Damon Morda based on information provided by Juniper Networks.

Other Information

CVE IDs: None
Severity Metric: 4.62
Date Public: 2004-08-03
Date First Published: 2004-08-13
Date Last Updated: 2004-08-13 16:56 UTC
Document Revision: 21

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