452 lines
21 KiB
Text
452 lines
21 KiB
Text
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN" [
|
|
<!ENTITY base CDATA "..">
|
|
<!ENTITY date "$Date: 1998-12-19 09:55:30 $">
|
|
<!ENTITY title "FreeBSD Security Information">
|
|
<!ENTITY % includes SYSTEM "../includes.sgml"> %includes;
|
|
]>
|
|
<!-- $Id: security.sgml,v 1.9 1998-12-19 09:55:30 jkh Exp $ -->
|
|
|
|
<html>
|
|
&header;
|
|
|
|
<H2>Introduction</H2>
|
|
|
|
<P>This web page is designed to assist both new and experienced users
|
|
in the area of security for the FreeBSD Operating System. The FreeBSD
|
|
Development team takes security very seriously and is constantly working
|
|
on making the OS as secure as possible.</P>
|
|
|
|
<P>Here you will find additional information, or links to information,
|
|
on how to protect your system against various types of outside attack,
|
|
whom to contact if you find a security related bug, etc. There is
|
|
also a section on the various ways that the systems programmer can
|
|
become more security conscious so he or she is less likely to
|
|
introduce security holes in the first place.</P>
|
|
|
|
<H2>Table Of Content</H2>
|
|
<UL>
|
|
<LI><A HREF="#sec">Information about the FreeBSD Security Officer</A></LI>
|
|
<LI><A HREF="#adv">FreeBSD Security Advisories</A></LI>
|
|
<LI><A HREF="#ml">FreeBSD Security Mailing Lists Information</A></LI>
|
|
<LI><A HREF="#tat">FreeBSD Security Tips and Tricks</A></LI>
|
|
<LI><A HREF="#spg">Secure Programing Guidelines</A></LI>
|
|
<LI><A HREF="#misc">Other Related Security Information</A></LI>
|
|
</UL>
|
|
|
|
<A NAME=sec></A>
|
|
<H2>The FreeBSD Security Officer</H2>
|
|
|
|
<P>To better coordinate information exchange with others in the security
|
|
community, FreeBSD has a focal point for security related communications:
|
|
The FreeBSD <a href="mailto:security-officer@freebsd.org">security officer</a>.
|
|
The position is actually staffed by a team of dedicated security officers,
|
|
their main tasks being to send out advisories when there are known security
|
|
holes and to act on reports of possible security problems with FreeBSD.</P>
|
|
|
|
<P>If you need to contact someone from the FreeBSD team about a
|
|
possible security bug, you should therefore please <A
|
|
HREF="mailto:security-officer@FreeBSD.org">send mail to the Security Officer</A>
|
|
with a description of what you've found and the type of vulnerability it
|
|
represents. The Security Officers also communicate with the various
|
|
<A HREF="http://www.cert.org">CERT </A>and <A
|
|
HREF="http://www.first.org/"> FIRST</A> teams around the world,
|
|
sharing information about possible vulnerabilities in FreeBSD or
|
|
utilities commonly used by FreeBSD. The Security Officers are also
|
|
active members of those organizations.</P>
|
|
|
|
<P>If you do need to contact the Security Officer about a particularly
|
|
sensitive matter, please use their <A
|
|
HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/public_key.asc">PGP key
|
|
</A> to encrypt your message before sending it.</P>
|
|
|
|
<A NAME=adv></A>
|
|
<H2>FreeBSD Security Advisories</H2>
|
|
|
|
<P>The FreeBSD Security Officers provide security advisories for the
|
|
following releases of FreeBSD:</P>
|
|
|
|
<UL>
|
|
<LI> The most recent official release of FreeBSD.
|
|
<LI> FreeBSD-current.
|
|
<LI> FreeBSD-stable, when at least 2 releases are based on it.
|
|
<LI> The previous FreeBSD-stable when a "new stable" does not yet
|
|
have 2 releases based on it.
|
|
</UL>
|
|
|
|
At this time, security advisories are available for:
|
|
<UL>
|
|
<LI> FreeBSD 2.2.7
|
|
<LI> FreeBSD 2.2.8
|
|
<LI> FreeBSD 3.0
|
|
<LI> FreeBSD-current
|
|
<LI> FreeBSD-stable
|
|
</UL>
|
|
|
|
<P>Older releases are not maintained and users are strongly encouraged
|
|
to upgrade to one of the supported releases mentioned above.</P>
|
|
|
|
<P>Like all development efforts, security fixes are first brought into
|
|
the <A HREF="../handbook/current.html">FreeBSD-current</A> branch.
|
|
After a couple of days and some testing, the fix is retrofitted into
|
|
the supported FreeBSD-stable branch(es) and an advisory then sent
|
|
out.</P>
|
|
|
|
<P>Advisories are sent to the following FreeBSD mailing lists:
|
|
<UL>
|
|
<LI>FreeBSD-security-notifications@freebsd.org
|
|
<LI>FreeBSD-security@freebsd.org
|
|
<LI>FreeBSD-announce@freebsd.org
|
|
</UL>
|
|
|
|
|
|
<P>Advisories are always signed using the FreeBSD Security Officer
|
|
<A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/public_key.asc"> PGP key
|
|
</A> and are archived, along with their associated patches, at our
|
|
<A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/index.html">FTP CERT
|
|
repository</A>. At the time of this writing, the following advisories are
|
|
currently available:</P>
|
|
|
|
<UL>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-96:01.sliplogin.asc">FreeBSD-SA-96:01.sliplogin.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-96:02.apache.asc">FreeBSD-SA-96:02.apache.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-96:03.sendmail-suggestion.asc">FreeBSD-SA-96:03.sendmail-suggestion.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-96:08.syslog.asc">FreeBSD-SA-96:08.syslog.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-96:09.vfsload.asc">FreeBSD-SA-96:09.vfsload.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-96:10.mount_union.asc">FreeBSD-SA-96:10.mount_union.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-96:11.man.asc">FreeBSD-SA-96:11.man.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-96:12.perl.asc">FreeBSD-SA-96:12.perl.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-96:13.comsat.asc">FreeBSD-SA-96:13.comsat.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-96:14.ipfw.asc">FreeBSD-SA-96:14.ipfw.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-96:15.ppp.asc">FreeBSD-SA-96:15.ppp.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-96:16.rdist.asc">FreeBSD-SA-96:16.rdist.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-96:17.rzsz.asc">FreeBSD-SA-96:17.rzsz.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-96:18.lpr.asc">FreeBSD-SA-96:18.lpr.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-96:19.modstat.asc">FreeBSD-SA-96:19.modstat.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-96:20.stack-overflow.asc">FreeBSD-SA-96:20.stack-overflow.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-96:21.talkd.asc">FreeBSD-SA-96:21.talkd.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-97:01.setlocale">FreeBSD-SA-97:01.setlocale</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-97:02.lpd.asc">FreeBSD-SA-97:02.lpd.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-97:03.sysinstall.asc">FreeBSD-SA-97:03.sysinstall.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-97:04.procfs.asc">FreeBSD-SA-97:04.procfs.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-97:05.open.asc">FreeBSD-SA-97:05.open.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-97:06.f00f.asc">FreeBSD-SA-97:06.f00f.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-98:01.land.asc">FreeBSD-SA-98:01.land.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-98:02.mmap.asc">FreeBSD-SA-98:02.mmap.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-98:03.ttcp.asc">FreeBSD-SA-98:03.ttcp.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-98:04.mmap.asc">FreeBSD-SA-98:04.mmap.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-98:05.nfs.asc">FreeBSD-SA-98:05.nfs.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-98:06.icmp.asc">FreeBSD-SA-98:06.icmp.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-98:07.rst.asc">FreeBSD-SA-98:07.rst.asc</A></LI>
|
|
<LI><A HREF="ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-98:08.fragment.asc">FreeBSD-SA-98:08.fragment.asc</A></LI>
|
|
</UL>
|
|
|
|
<A NAME=ml></A>
|
|
<H2>FreeBSD Security Mailing Lists Information</H2>
|
|
|
|
<P>If you are administering or using any number of FreeBSD systems, you
|
|
should probably be subscribed to one or more of the following lists:</P>
|
|
|
|
<PRE>
|
|
freebsd-security General security related discussion
|
|
freebsd-security-notification Security notifications (moderated mailing list)
|
|
</PRE>
|
|
|
|
Send mail to <A HREF="mailto:majordomo@freebsd.org">
|
|
majordomo@FreeBSD.ORG</A> with
|
|
<PRE>
|
|
subscribe <listname> [<optional address>]
|
|
</PRE>
|
|
in the body of the message in order to subscribe yourself.
|
|
For example:
|
|
<PRE>
|
|
% echo "subscribe freebsd-security" | mail majordomo@freebsd.org
|
|
</PRE>
|
|
and if you would like to unsubscribe from a mailing list:
|
|
<PRE>
|
|
% echo "unsubscribe freebsd-security" | mail majordomo@freebsd.org
|
|
</PRE>
|
|
|
|
<A NAME=spg></A>
|
|
<H2>Secure Programing Guidelines</H2>
|
|
<P><P><UL>
|
|
<LI>Never trust any source of input, i.e. command line arguments,
|
|
environment variables, configuration files, incoming TCP/UDP/ICMP packets,
|
|
hostname lookups, function arguments, etc. If the length of or contents of
|
|
the date received is at all subject to outside control, then the program or
|
|
function should watch for this when copying it around. Specific security
|
|
issues to watch for in this are are:
|
|
<P></P>
|
|
<UL>
|
|
|
|
<LI>strcpy() and sprintf() calls from unbounded data. Use strncpy and
|
|
snprintf() when the length is known (or implement some other form of
|
|
bounds-checking when the length is unknown). In fact, never ever use
|
|
gets() or sprintf(), period. If you do - will send evil dwarfs after you.
|
|
<P></P></LI>
|
|
|
|
<LI>If you have to check the user input so it does not contain bad
|
|
characters of some sort, do NOT check for those bad characters. Instead
|
|
simply verify that it consists ONLY of those characters that you do
|
|
allow. In general concept is: disallow anything that is not
|
|
explicitly allowed.
|
|
<P></P></LI>
|
|
|
|
<LI>Read man pages for strncpy() and strncat() calls. Be sure to
|
|
understand how they work!!! While strncpy() might not append a terminating
|
|
\0, strncat() on the other hand adds the \0.
|
|
<P></P></LI>
|
|
|
|
<LI>Watch for strvis() and getenv() abuse. With strvis() it is easy to get
|
|
the destination string wrong for, and getenv() can return strings much
|
|
longer then the program might expect. These two functions are one of the
|
|
key ways an attack is often made on a program, causing it to overwrite stack
|
|
or variables by setting its environment variables to unexpected values. If
|
|
your program reads environment variables, be paranoid. Be very paranoid!
|
|
<P></P></LI>
|
|
|
|
<LI>Ever time you use open() or stat() call - ask yourself: "What if it
|
|
is a symbolic link?"
|
|
<P></P></LI>
|
|
|
|
<LI>Make sure to use mkstemp() instead of mktemp(), tempnam(), mkstemp() and
|
|
etc. Also make sure to look for races in /tmp in general, being aware that
|
|
there are very few things which can be atomic in /tmp:
|
|
<UL>
|
|
<LI>Creating a directory. This will either succeed or fail.</LI>
|
|
<LI>Opening a file O_CREAT | O_EXECL</LI>
|
|
</UL>
|
|
If you use mkstemp - above cases will be properly handled for you. Hence
|
|
all temp files should use mkstemp() to guarantee there is not race
|
|
condition and that the permissions are correct.
|
|
<P></P></LI>
|
|
|
|
<LI>If an attacker can force packets to go/come from another arbitrary
|
|
system then that attacker has complete control over the data that we get
|
|
and <B>NONE</B>of it should be trusted.
|
|
<P></P></LI>
|
|
|
|
<LI>Never trust a configuration file is correctly formatted or that it was
|
|
generated by the appropriate utility. Don't trust user input such as
|
|
terminal names or language strings to be free of '/' or '../../../' if
|
|
there is any chance that they can be used in a path name. Don't trust
|
|
<B>ANY</B> paths supplied by the user when you are running setuid root.
|
|
<P></P></LI>
|
|
|
|
<LI>Look for holes or weaknesses in how data is stored. All temp files
|
|
should have 600 permission in order to be protected from prying eyes.
|
|
<P></P></LI>
|
|
|
|
<LI>Don't just grep for the usual suspects in programs which run with
|
|
elevated privileges. Look line by line for possible overflows in these
|
|
cases since there are a lot more ways to cause buffer overflows then
|
|
by abusing strcpy() and friends.
|
|
<P></P></LI>
|
|
|
|
<LI>Just because you drop privileges somewhere, it does not mean that no
|
|
exploit is possible. The attacker may put the necessary code on the
|
|
stack to regain the privileges before executing /bin/sh.</LI></UL>
|
|
<P></P></LI>
|
|
|
|
<LI>Do uid management. Do drop privileges as soon as possible, and really
|
|
do drop them. Switching between euid and uid is NOT enough. Use setuid()
|
|
when you can.
|
|
<P></P></LI>
|
|
|
|
<LI>Never display configuration file contents on errors. A line number and
|
|
perhaps position count is enough. This is true for all libs and for any
|
|
suid/sgid program.
|
|
<P></P></LI>
|
|
|
|
<LI>Tips for those reviewing existing code for security problems:<P></P><UL>
|
|
|
|
<LI>If you are unsure of your security fixes, send them to a reviewer with
|
|
whom you have already arrangements for a second glance over your
|
|
code. Don't commit code you are not sure about since breaking something
|
|
in the name of security fix is rather embarrassing.
|
|
<P></P></LI>
|
|
|
|
<LI>Those without CVS commit privileges should make sure that a reviewer
|
|
with such privileges is among the last to review the changes. That person
|
|
will both review and incorporate the final version you would like to have
|
|
go into the tree.
|
|
<P></P></LI>
|
|
|
|
<LI>When sending changes around for review, always use context or unidiff
|
|
format diffs - this way diffs can be easily fed to patch(1). Do not simply
|
|
send the whole files. Diffs are much easier to read and apply to local
|
|
sources (especially those in which multiple, simultaneous changes may be
|
|
taking place). All changed should be relative to the -current branch of
|
|
development.
|
|
<P></P></LI>
|
|
|
|
<LI>Always directly test your changes (e.g. build and run the affected
|
|
sources) before sending them to a reviewer. Nobody likes being sent
|
|
obviously broken stuff for review, and it just makes it appear as though
|
|
the submitter didn't even really look at what he was (which is also hardly
|
|
confidence building). If you need accounts on a machine with a specific
|
|
version which you don't have available - just ask. The project has
|
|
resources available for exactly such purposes.
|
|
<P></P></LI>
|
|
|
|
<LI>Note for committers: do not forget to retrofit -current patches into
|
|
the -stable branch as appropriate.
|
|
<P></P></LI>
|
|
|
|
<LI>Do not needlessly rewrite code to suit your style/tastes - it only
|
|
makes the reviewer's job needlessly more difficult. Do so only if there
|
|
are clear reasons for it.</LI></UL
|
|
<P></P></LI>
|
|
|
|
<LI>Look out for programs doing complex things in with signal
|
|
handlers. Many routines in the various libraries are not sufficiently
|
|
reentrant to make this safe.
|
|
<P></P></LI>
|
|
|
|
<LI>Pay special attention to realloc() usage - more often then not the
|
|
function is not used correctly.
|
|
<P></P></LI>
|
|
|
|
<LI>When using a fixed size buffers, use sizeof() to prevent lossage
|
|
when a buffer size is changed but the code which uses it isn't. For
|
|
example:
|
|
<LISTING>
|
|
char buf[1024];
|
|
struct foo { ... };
|
|
...
|
|
BAD:
|
|
xxx(buf, 1024)
|
|
xxx(yyy, sizeof(struct foo))
|
|
GOOD:
|
|
xxx(buf, sizeof(buf))
|
|
xxx(yyy, sizeof(yyy))
|
|
</LISTING>
|
|
Be careful though with sizeof of pointers when you really want the size
|
|
of where it points to!
|
|
<P></P></LI>
|
|
|
|
<LI>Every time you see "char foo[###]", check every usage of foo to make
|
|
sure that it can't be overflowed. If you can't avoid overflow (and cases
|
|
of this have been seen), then at least malloc the buffer so that one can't
|
|
walk on the stack.
|
|
<P></P></LI>
|
|
|
|
<LI>Always close file descriptors as soon as you can - this makes it more
|
|
likely that the stdio buffer contents will be discarded. In library
|
|
routines, always set any file descriptors that you open to close-on-exec.
|
|
<P><P></LI>
|
|
</UL>
|
|
|
|
<A NAME=tat></A>
|
|
<H2>FreeBSD Security Tips and Tricks</H2>
|
|
<P>There are several steps one must take to secure a FreeBSD system, or
|
|
in fact any Unix system:
|
|
<UL>
|
|
|
|
<LI>Disabling potentially dangerous software<BR><P></P>
|
|
A lot of software has to be run as a special privileged user to make
|
|
use of specific resources, by making the executable set-uid. An
|
|
example is UUCP or PPP software that makes use of a serial port, or
|
|
sendmail which has to write in the mail spool and bind to a privileged
|
|
network port. When you are not using UUCP, it is of little use to have
|
|
software on your system and it may be wise to disable it. Of course,
|
|
this requires good knowledge of what can be thrown away and what not,
|
|
as well as good indication whether or not you will want the functionality
|
|
in the future.<BR><P></P>
|
|
Also some utilities you may find not useful enough to have them
|
|
around and pose a possible security risk, like swapinfo. If you remove
|
|
the set-uid bit for the executable (via 'chmod ug-s filename' command)
|
|
you can always keep on using swapinfo when you're root. It is however
|
|
not a good idea stripping so many sbits you have to be root all
|
|
the time.<BR><P></P>
|
|
Not only remove programs that you don't use, also remove services you
|
|
don't want or need to provide. This can be done by editing the
|
|
<TT>/etc/inetd.conf</TT> and <TT>/etc/rc.conf</TT> files and turning
|
|
off all services you don't use.<P></P>
|
|
|
|
<LI>Fixing software which has security bugs (or how to stay one step ahead
|
|
of crackers)<BR><P></P>
|
|
Make sure you are subscribed to various <A HREF="#ml">FreeBSD Security
|
|
mailing lists</A> so you could get updates on security bugs and get
|
|
fixes. Apply the fixes immediately.<P></P>
|
|
|
|
<LI>Backups - repair your system if security breach does occur<BR><P></P>
|
|
Always have backups and a clean version of the operating system (e.g. on
|
|
CD-Rom). Make sure your backups don't contain corrupted or modified by
|
|
attackers data.<P></P>
|
|
|
|
<LI>Install software to watch the state of the system<BR><P></P>
|
|
Programs like the tcp wrappers and tripwire (both in packages/ports) can
|
|
help you to monitor activity on your system. This makes it easier
|
|
to detect break-ins. Also read outputs of the /etc/security scripts
|
|
which are run daily and mailed to the root account.<P></P>
|
|
|
|
<LI>Educating the people who work on the system<BR><P></P>
|
|
Users should know that they are doing. They should be told to never give
|
|
out their password to anyone and to also use hard to guess passwords.
|
|
Let them understand that the security of the system/network is partly
|
|
in their hands.<P></P>
|
|
</UL>
|
|
|
|
|
|
<P>There is also a FreeBSD Security How-To available which provides some
|
|
advanced tips on how to improve security of your system. You can
|
|
find it at <A HREF="http://www.freebsd.org/~jkb/howto.html">
|
|
http://www.freebsd.org/~jkb/howto.html</A>.</P>
|
|
<P>Security is an ongoing process. Make sure you are following the latest
|
|
developments in the security arena.</P>
|
|
|
|
<A NAME=misc></A>
|
|
<H2>What to do when you detect a security compromise</H2>
|
|
|
|
<UL>
|
|
<LI><B>Determine the level of the security breach</B><BR>
|
|
What privileges did the attacker get? Did the attacker managed to get
|
|
root access? Did the attacker only managed to get user level access?</LI>
|
|
|
|
<LI><B>Determine if the state of system (kernel or userland) has been
|
|
tampered with</B><BR>
|
|
What software has been tampered with? Was new kernel installed? Were any
|
|
of the system binaries (such as telnetd, login, etc) modified? If you
|
|
believe an attacker could have done any tampering with an OS, you may want
|
|
to re-install the operating system from a safe medium.</LI>
|
|
|
|
<LI><B>Find out how the break-in was done</B><BR>
|
|
Did the breaking occur via a well know security bug? If that is the case,
|
|
make sure to install the correct patches. Was the breaking successful due
|
|
to a misconfiguration? Was the breakin result of a new bug? If you believe
|
|
the breakin occurred via a new bug, you should warn the
|
|
<A HREF="mailto:security-officer@freebsd.org"> FreeBSD Security
|
|
Officer</A>.</LI>
|
|
|
|
<LI><B>Fix the security hole</B><BR>
|
|
Install new software or apply patches to the old one in order to fix the
|
|
problems. Disable already compromised accounts.</LI>
|
|
|
|
<LI><B>Other resources</B><BR>
|
|
<A HREF="http://www.cert.org">CERT</A> also offers
|
|
<A HREF="http://www.cert.org/nav/recovering.html">detailed information</A>
|
|
on what steps to take in case of a system compromise.</LI>
|
|
</UL>
|
|
|
|
<H2>Other Related Security Information</H2>
|
|
<UL>
|
|
<LI><A href="http://www.cs.purdue.edu/coast/archive/index.html">The COAST
|
|
archive</A> contains a huge collection of security related materials.</LI>
|
|
|
|
<LI><A href="http://www.cs.purdue.edu/coast/hotlist/">The COAST Security
|
|
Hotlist</A> is the place to start looking for security related materials.
|
|
It contains hundreds of useful security pointers. Everything you always
|
|
wanted to know about security... and more.</LI>
|
|
|
|
<LI>The various CERT teams such as <A href="http://www.cert.org">
|
|
http://www.cert.org</A> and <A href="http://www.auscert.org.au">
|
|
http://www.auscert.org.au</A>.</LI>
|
|
|
|
<LI>Mailing lists such as <A HREF="http://www.geek-girl.com/bugtraq/">
|
|
Bugtraq</A> and <A HREF="http://www.nfr.net/forum/firewall-wizards.html">
|
|
Firewall Wizards</A>.</LI>
|
|
</UL>
|
|
|
|
&footer
|
|
</body>
|
|
</html>
|