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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>There seems to a new way of installating shellbots into the
/tmp directory on the server and im not positive on how it’s being done.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I’v noticed this on 2 of my client’s servers in
the past few weeks.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>What strange about it is mod_security has not caught it. Now
we install a fairly complicated version of the rules on our client’s
servers. It include lynx, at least 3 variations and in /usr/bin/lynx is chmod
750 yet it seems that this is how its being installed at the moment.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I cant understand how lynx –lp is being executed. If
its chmod 750 nobody from the internet can execute the command. Why do I think
its lynx –lp? Because I killed a pid that was executing lynx –lp as
the user nobody.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>They did not get far. The firewall denies all outbound
connections and these bots usually try to make a connection outbound on port
6667. Even so, im frustrated as hell trying to find out how it’s being
done. I searched all the user logs using egrep and could not find an occurrence
of lynx –lp but it was definitely there and the firewall did tell me that
it was a suspicious process running.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I’m also surprised that our mod_sec rules which is
about 57k did not catch it. If it was used as a cmd= or whatever both cmd and
lynx does exist in the rules and the fact that lynx, wget, scp etc is all chmod
750 is a mystery too me.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Unless its being installed some other way other than via a malicious
url I have no idea how its getting dumped to /tmp.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Anyone?<o:p></o:p></span></font></p>
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