Microsoft's Network Monitor - Buffer Overrun / Page Fault /

From: mnemonix (mnemonixat_private)
Date: Sat Dec 12 1998 - 13:49:16 PST

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    There is a problem with both the SMS version of Network Monitor and the =
    version on the NT Server 4 CD-ROM whereby if it "sniffs" a NetBIOS =
    session request from a machine where the NetBIOS Scope ID is 190 or more =
    characters when the capture is stopped and the results are viewed the =
    Network Monitor process (netmon.exe) experiences a memory problem. =
    Depending on whether there are other open capture windows or not the =
    memory problem manifests itself in a number of different ways - =
    sometimes buffer overruns, some times a page fault and others the =
    process just dies with no reason as to why.
    
    The problem actually stems from the netbios parser - netbios.dll - not =
    being able to handle the packet when it tries to interpret the contents.
    
    The impact of this problem can be from a simple Denial of Service to =
    really annoy an admin trying to troubleshoot a LAN issue - to possible =
    exploitation - especially as Network Monitor is normally run by an Admin =
    and conseqently the netmon.exe process and any child process it spawns =
    will run with Administrative privileges.
    
    Microsoft was informed about this issue around 8 weeks ago, but not =
    having heard anything since the first conversation I had wth them about =
    this I am issuing this advisory.
    
    This was tested on NT Server 4.0 (Service Pack Three + Hotfixes) and =
    Windows 95.
    
    Cheers,
    
    David Litchfield
    
    http://www.infowar.co.uk/mnemonix/
    
    
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    <P>There is a problem with both the SMS version of Network Monitor and =
    the=20
    version on the NT Server 4 CD-ROM whereby if it &quot;sniffs&quot; a =
    NetBIOS=20
    session request from a machine where the NetBIOS Scope ID is 190 or more =
    
    characters when the capture is stopped and the results are viewed the =
    Network=20
    Monitor process (netmon.exe) experiences a memory problem. Depending on =
    whether=20
    there are other open capture windows or not the memory problem manifests =
    itself=20
    in a number of different ways - sometimes buffer overruns, some times a =
    page=20
    fault and others the process just dies with no reason as to why.</P>
    <P>The problem actually stems from the netbios parser - netbios.dll - =
    not being=20
    able to handle the packet when it tries to interpret the contents.</P>
    <P>The impact of this problem can be from a simple Denial of Service to =
    really=20
    annoy an admin trying to troubleshoot a LAN issue - to possible =
    exploitation -=20
    especially as Network Monitor is normally run by an Admin and =
    conseqently the=20
    netmon.exe process and any child process it spawns will run with =
    Administrative=20
    privileges.</P>
    <P>Microsoft was informed about this issue around 8 weeks ago, but not =
    having=20
    heard anything since the first conversation I had wth them about this I =
    am=20
    issuing this advisory.</P>
    <P>This was tested on NT Server 4.0 (Service Pack Three + Hotfixes) and =
    Windows=20
    95.</P>
    <P><FONT face=3DArial></FONT>Cheers,</P>
    <P><FONT face=3DArial>David Litchfield</FONT></P>
    <P><FONT=20
    face=3DArial>http://www.infowar.co.uk/mnemonix/></P></FONT></DIV></=
    BODY></HTML>
    
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