Author: Benjamin D. Thomas
Security Compromise Underway?
By: Dave Wreski
Spotting a security compromise under way can be a tense
undertaking. How you react can have large consequences.
If the compromise you are seeing is a physical one, odds are you
have spotted someone who has broken into your home, office or lab.
You should notify your local authorities. In a lab, you might have
spotted someone trying to open a case or reboot a machine.
Depending on your authority and procedures, you might ask them to
stop, or contact your local security people.
If you have detected a local user trying to compromise your
security, the first thing to do is confirm they are in fact who you
think they are. Check the site they are logging in from. Is it the
site they normally log in from? No? Then use a non-electronic means
of getting in touch. For instance, call them on the phone or walk
over to their office/house and talk to them. If they agree that
they are on, you can ask them to explain what they were doing or
tell them to cease doing it. If they are not on, and have no idea
what you are talking about, odds are this incident requires further
investigation. Look into such incidents , and have lots of
information before making any accusations.
If you have detected a network compromise, the first thing to do
(if you are able) is to disconnect your network. If they are
connected via modem, unplug the modem cable; if they are connected
via Ethernet, unplug the Ethernet cable. This will prevent them
from doing any further damage, and they will probably see it as a
network problem rather than detection.
If you are unable to disconnect the network (if you have a busy
site, or you do not have physical control of your machines), the
next best step is to use something like tcp_wrappers or ipfwadm to
deny access from the intruder’s site.
If you can’t deny all people from the same site as the intruder,
locking the user’s account will have to do. Note that locking an
account is not an easy thing. You have to keep in mind .rhosts
files, FTP access, and a host of possible backdoors.
After you have done one of the above (disconnected the network,
denied access from their site, and/or disabled their account), you
need to kill all their user processes and log them off.
You should monitor your site well for the next few minutes, as
the attacker will try to get back in. Perhaps using a different
account, and/or from a different network address.
Read more from the Linux Security Howto:
http://www.linuxsecurity.com/docs/LDP/Security-HOWTO/
Debian | ||
Debian: New Mozilla packages fix several vulnerabilities |
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20th, October, 2005
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Debian: New module-assistant package fixes insecure temporary file |
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20th, October, 2005
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Debian: New Mozilla Thunderbird packages fix several vulnerabilities |
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20th, October, 2005
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Debian: New eric packages fix arbitrary code execution |
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21st, October, 2005
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Debian: New sudo packages fix arbitrary command execution |
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Debian: New libgda2 packages fix arbitrary code execution |
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25th, October, 2005
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Debian: New libgda2 packages fix arbitrary code execution |
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25th, October, 2005
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Debian: New imlib packages fix arbitrary code execution |
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26th, October, 2005
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Debian: New koffice packages fix arbitrary code execution |
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26th, October, 2005
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Debian: New net-snmp packages fix denial of service |
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26th, October, 2005
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Debian: New lynx packages fix arbitrary code execution |
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27th, October, 2005
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Debian: New OpenSSL packages fix cryptographic weakness |
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27th, October, 2005
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Gentoo | ||
Gentoo: AbiWord New RTF import buffer overflows |
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Gentoo: Netpbm Buffer overflow in pnmtopng |
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Gentoo: cURL NTLM username stack overflow |
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22nd, October, 2005
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Gentoo: Zope File inclusion through RestructuredText |
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Gentoo: phpMyAdmin Local file inclusion and XSS vulnerabilities |
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25th, October, 2005
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Red Hat | ||
RedHat: Moderate: ethereal security update |
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25th, October, 2005
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RedHat: Low: pam security update |
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26th, October, 2005
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RedHat: Low: fetchmail security update |
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26th, October, 2005
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