[rootshell] Security Bulletin #23

From: Aleph One (aleph1at_private)
Date: Mon Sep 14 1998 - 14:17:27 PDT

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    Subject: [rootshell] Security Bulletin #23
    
    
    www.rootshell.com
    Security Bulletin #23
    September 14th, 1998
    
    [ http://www.rootshell.com/ ]
    
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    01. Osicom Technologies ROUTERmate Security Advisory
    ----------------------------------------------------
    
    Osicom Technologies (http://www.osicom.com) makes remote access router
    products for 56K-T1 users.  While evaluating these products Rootshell came
    across various flaws in the TCP/IP stack of these routers allowing remote
    users to gain access to and crash the ROUTERmate products.
    
    Products affected
    -----------------
    
    * ROUTERmate Plus T1
    * ROUTERmate Plus 56K
    * ROUTER mate-EX MULTI-PROTOCOL EXECUTIVE ROUTER
    * ROUTER mate Plus - D&I INTEGRATED ROUTER AND T-1 DROP & INSERT CSU
    
    List of problems
    ----------------
    
    * The TCP/IP stack deals with SYN packets incorrectly and allows a remote
    user to crash the unit in two ways.  In each of these cases the router will
    reboot and then function normally unless hit with the attack again.
    
      1) If a user port scans the router with any readily available port scanner
      the unit will crash.
    
      2) If the router is hit with a flood of SYN packets the router crashes.
      Code to generate SYN packets can be found on the Rootshell website as
      "synk4.c" and "SYNpacket.tgz".
    
    * The TCP/IP stack can be crashed by exploiting the "off by one" IP header
    bug that recently affected Linux and Windows users.  This attack is commonly
    know as "nestea.c" and can be found on Rootshell.  The ROUTERmate will also
    crash with the similar bugs "bonk.c" and "newtear.c".  After these attacks
    the router will reboot then function normally unless hit with the attack
    again.
    
    * The TCP/IP stack can be caused to completely freeze up requiring a reboot
    by the end user via the serial port console or by bouncing the units power
    source.  "pmcrash.c" available on Rootshell crashes Livingston portmasters
    prior to ComOS 3.3.1 (they fixed this problem well over a year ago).  This
    same problem is now in the ROUTERmate product, however the unit will not
    reboot on its own.  On a local network we were able to crash the ROUTERmate
    after running pmcrash for just a few seconds.  pmcrash.c simply sends large
    amounts of fragmented ICMP traffic at the router.
    
    * The default SNMP configuration allows any remote user to change the
    configuration of leased lines, place circuits in loopback, and reboot the
    router.  The ROUTERmate product ships with a default write community of
    "private".  By using commonly available SNMP software such as the CMU SNMP
    packages a user can gain access to the following commands.  The entire MIB
    file can be found on ftp.osicom.com.
    
    unitResetCommand   <------ Anyone can reboot the product by default.
    localNIloop
    remoteNIloop
    lineLoop
    payloadLoop
    testPattern
    niClearTestCounter
    insertBitError
    interfaceLocalLoop
    interfaceRemoteLoopWithTestPattern
    interfaceTestPattern
    interfaceDiagClearCounters
    saveConfigToFlash
    niFormat
    niCoding
    niTiming
    niLineBuildOut
    esfDataLink
    remoteLoop
    esfCxrLoops
    bandwidthAlloc
    interfaceDataRate
    interfaceDataMode
    interfaceRmtLoopResponse
    clearCounters
    clientAutoLearn
    accessViaTelnet
    clientAddress
    
    This problem is not unique to Osicom.  Rootshell after 2 years of e-mails to
    Ascend (http://www.ascend.com/) got them to turn off the write community in
    their products and added the "R/W Comm Enable" setting in their SNMP
    configuration area.
    
    Since the ROUTERmate product does not support packet filters the only
    workaround at the moment is to disable the "Autolearn Clients" feature of
    the ROUTERmate.
    
    Solution
    --------
    
    Osicom was informed of these problems on July 31st, 1998.
    
    New firmware when available should be posted to :
    
    ftp://ftp.osicom.com/
    
    Vendor Contact
    --------------
    
    Osicom Technologies Inc., 2800
    28th Street, Suite 100
    Santa Monica, CA 90405 USA
    
    infoat_private
    888-674-2668 (888-Osicom-8)
    
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