Rule:

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Sid:
1329

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Summary:
This event is generated when an attempt is made to access the ps command
via the web

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Impact:
Attempt to gain information on system processes on webserver

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Detailed Information:
This is an attempt to gain intelligence on the processes being run on a
webserver. The ps command lists the process status of running processes
on a UNIX or Linux based system. The attacker could possibly gain
information needed for other attacks on the system.

Using "ps", the attackers would check for various running system
services to exploit or for the presence of security software, such as
host IDS or monitoring scripts. This rule looks for the "ps" command in
the URI part of the client to web server connection and does not
indicate whether the command was actually successful in displaying the
list of processes. The presence of the "ps" command in the URI indicates
that an attacker attempted to trick the web server into executing system
commands in non-interactive mode i.e. without a valid shell session.

Alternatively this rule may trigger in an unencrypted HTTP tunneling
connection to the server or a shell connection via another exploit
against the web server.

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Attack Scenarios:
The attacker can make a standard HTTP request that contains '/bin/ps'in
the URI.

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Ease of Attack:
Simple HTTP request.

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False Positives:
None Known

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False Negatives:
None Known

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Corrective Action:

Webservers should not be allowed to view or execute files and binaries
outside of it's designated web root or cgi-bin. This command may also be
requested on a command line should the attacker gain access to the
machine. On BSD derived systems, setting the parameter
"kern.ps_showallprocs" to zero will show only the processes being run by
that user except for root who will still see all processes.

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Contributors:
Sourcefire Research Team
Nigel Houghton <nigel.houghton@sourcefire.com>
Additional information from Anton Chuvakin <http://www.chuvakin.org>

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Additional References:
sid: 1328

Manual page for ps.

http://linux.about.com/library/cmd/blcmdl1_ps.htm

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