NetScreen ScreenOS 2.6 Subject to Trust Interface DoS

From: Chris Lathem (clathemat_private)
Date: Fri Feb 01 2002 - 07:06:49 PST

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    Problem: NetScreen ScreenOS 2.6.1 subject to Trust 
    Interface DoS Attack
    
    Company Info: NetScreen Technologies are the 
    manufacturers of some of the industry's highest 
    quality VPN and firewall equipment. For more 
    information please see http://www.netscreen.com.
    
    What's affected: The ScreenOS is the heart of the 
    NetScreen products. This allows for the firewall 
    configuration/management. Apparently all versions 
    before ScreenOS 3.1 are affected. This vulnerability 
    can only occur from within the "trusted" network, or 
    from a machine connected to the "trust" interface. 
    External attempts will not cause any problems/DoS.
    
    Exploit: Someone within the trusted side of the 
    network can attempt a portscan on an external IP 
    address. When the scan runs it appears to consume 
    all of the available sessions. This, in turn, causes a 
    DoS to the entire trusted interface. The only way I got 
    my device to recover quickly was to perform a reset. 
    A recovery might be possible without a reset, but 
    after about 5 minutes of waiting, mine never 
    recovered. This exploit may or may not work on your 
    device. My testing was performed on a NetScreen 5. 
    The higher-end, more pricier models may take longer 
    to "eat up" all the available sessions, thus taking 
    longer for a DoS to occur. 
    
    I have contacted NetScreen in regards to the issue. I 
    received a response back that the problem is a 
    known issue. It has been addressed in ScreenOS 
    3.1. An update to ScreenOS 3.1 is available for 
    anyone with a NetScreen 200 or 500. For all other 
    models, the update to ScreenOS 3.1 will be available 
    on April 1, 2002.
    
    I'd love to hear if anyone else has noticed this, or if 
    other models are affected by this issue.
    
    Cheers,
    Chris Lathem
    chrisat_private
    http://www.lathemonline.com
    
    
     
    



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