Rule:

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Sid:
1337

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Summary:
Attempted chgrp command access via web

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Impact:
Attempt to change group permissions on a webserver.

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Detailed Information:
This is an attempt to change file permissions on a machine. Using this
command anattacker may change the permissions of a file to suit his
own needs,make a file readable, writeable or excutable to other groups
that wouldotherwise not have these special permissions.

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Attack Scenarios:
The attacker can make a standard HTTP request that contains '/bin/chgrp'
in the URIwhich can then change file permissions of files present on
the host.Thiscommand may also be requested on a command line should
the attacker gainaccess to the machine.

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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'sdesignated web root or cgi-bin.Whenever possible,
sensitive filesand certain areas of the filesystem should have the
system immutableflag set to negate the use of the chgrp command. On
BSD derived systems,setting the systems runtime securelevel also
prevents the securelevelfrom being changed. (note: the securelevel can
only beincreased)

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Contributors:
Sourcefire Research Team

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Additional References:
sid: 1336
sid: 1338

man chgrp

man chmod

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