Original issue date: April 3, 1995<BR>
Last revised: September 23, 1997<BR>
Updated Copyright statement

<P>A complete revision history is at the end of this file.

<P>The CERT Coordination Center staff examined beta version 0.51 of the
Security Administrator Tool for Analyzing Networks (SATAN). This advisory
initially contained information based on our review of this pre-release
version. When the official release became available, we updated the advisory
based on version 1.1.1.

<H4>1. What is SATAN?</H4>

SATAN is a testing and reporting tool that collects a variety of information
about networked hosts. The currently available documentation can be found
at<P> <A HREF="ftp://ftp.win.tue.nl/pub/security/satan_doc.tar.Z">ftp://ftp.win.tue.nl/pub/security/satan_doc.tar.Z</A>

<P>SATAN gathers information about specified hosts and networks by examining
network services (for example, finger, NFS, NIS, ftp, and rexd). It can
then report this data in a summary format or, with a simple rule-based
system, investigate potential security problems. Problems are described
briefly and pointers provided to patches or workarounds. In addition to
reporting vulnerabilities, SATAN gathers general network information (network
topology, network services run, types of hardware and software being used
on the network). As described in the SATAN documentation, SATAN has an
exploratory mode that allows it to probe hosts that have not been explicitly
specified. Thus, SATAN could probe not only targeted hosts, but also hosts
outside your administrative domain.

<P>Section 4 below lists the vulnerabilities currently probed by SATAN.

<P>After the release of SATAN 1.0, we published a separate advisory describing
a vulnerability in SATAN. If you do not already have a copy of CA-95.07a,
we strongly urge you to obtain a copy from

<A HREF="http://www.cert.org/advisories/CA-95.07a.REVISED.satan.vul.html">www.cert.org/advisories/CA-95.07a.REVISED.satan.vul.html</A>

<P>As we receive new information about SATAN, we will update advisories
CA-95.06 (SATAN in general) and CA-95.07a (vulnerability in SATAN). We
encourage you to check our advisories regularly for updates to relating
to your site.

<H4>2. Potential Impact of SATAN</H4>

SATAN was designed as a security tool for system and network administrators.
However, given its wide distribution, ease of use, and ability to scan
remote networks, SATAN is also likely to be used to locate vulnerable hosts
for malicious reasons. It is also possible that sites running SATAN for
a legitimate purpose will accidentally scan your system via SATAN's exploratory

<P>Although the vulnerabilities SATAN identifies are not new, the ability
to locate them with a widely available, easy-to-use tool increases the
level of threat to sites that have not taken steps to address those
vulnerabilities.  In addition, SATAN is easily extensible. After it is 
released, modified versions might scan for other vulnerabilities as well 
and might include code to compromise systems.

<H4>3. How to Prepare for the Release of SATAN</H4>
<LI>Examine your systems for the vulnerabilities described below and implement
security fixes accordingly.</LI>

<LI><P>In addition to reading the advisories cited for specific vulnerabilities
below, consult the following documents for guidance on improving the security
of your systems:</LI>

<A HREF="ftp://ftp.cert.org/pub/tech_tips/intruder_detection_checklist">ftp://ftp.cert.org/pub/tech_tips/intruder_detection_checklist</A><BR>
<A HREF="ftp://ftp.cert.org/pub/tech_tips/UNIX_configuration_guidelines">ftp://ftp.cert.org/pub/tech_tips/UNIX_configuration_guidelines</A><BR>
<A HREF="ftp://ftp.cert.org/pub/tech_tips/anonymous_ftp_config">ftp://ftp.cert.org/pub/tech_tips/anonymous_ftp_config</A><BR>
<A HREF="ftp://ftp.cert.org/pub/tech_tips/packet_filtering">ftp://ftp.cert.org/pub/tech_tips/packet_filtering</A><BR>

<LI><P>Contact your vendor for information on available security patches, and
ensure that all patches have been installed at your site.</LI>

<LI><P>Use the tools listed in Section 5 to assist you in assessing and improving
the security of your systems.</LI>
<H4>4. Vulnerabilities Probed by SATAN</H4>
Listed below are vulnerabilities that beta version 0.51 of SATAN tests
for, along with references to CERT advisories and other documents where

<P>Administrators should verify the state of their systems and perform
corrective actions as necessary. We cannot stress enough the importance
of good network configuration and the need to install all available patches.
<LI>NFS export to unprivileged programs

<LI>NFS export via portmapper

<LI>Unrestricted NFS export

<P>See CERT advisory <A HREF="http://www.cert.org/advisories/CA-94.15.NFS.Vulnerabilities.html">CA-94.15</A> for security measures you can take to address
NFS vulnerabilities.

<P>The following advisories also address problems related to NFS: 
<A HREF="http://www.cert.org/advisories/CA-94.02.REVISED.SunOS.rpc.mountd.vulnerability.html">CA-94.02.REVISED.SunOS.rpc.mountd.vulnerability</A><BR>
<A HREF="http://www.cert.org/advisories/CA-93.15.SunOS.and.Solaris.vulnerabilities.html">CA-93.15.SunOS.and.Solaris.vulnerabilities</A><BR>
<A HREF="http://www.cert.org/advisories/CA-92.15.Multiple.SunOS.vulnerabilities.patched.html">CA-92.15.Multiple.SunOS.vulnerabilities.patched</A><BR>
<A HREF="http://www.cert.org/advisories/CA-91.21.SunOS.NFS.Jumbo.and.fsirand.html">CA-91.21.SunOS.NFS.Jumbo.and.fsirand</A>

<LI>NIS password file access
<BR>See CERT advisory <A HREF="http://www.cert.org/advisories/CA-92.13.SunOS.NIS.vulnerability.html">CA-92.13</A> for information about SunOS 4.x machines using
NIS, and <A HREF="http://www.cert.org/advisories/CA-93.01.REVISED.HP.NIS.ypbind.vulnerability.html">CA-93.01</A> for information about HP machines.

<LI><P>rexd access<BR>
We recommend filtering the rexd service at your firewall and commenting
out rexd in the file /etc/inetd.conf.

<P>See CERT advisory <A HREF="http://www.cert.org/advisories/CA-92.05.AIX.REXD.Daemon.vulnerability.html">CA-92.05</A> for more information about IBM AIX machines
using rexd, and <A HREF="http://www.cert.org/advisories/CA-91.06.NeXTstep.vulnerability.html">CA-91.06</A> for information about NeXT.

<LI><P>Sendmail vulnerabilities<BR>
See CERT advisory CA-95.05 for the latest information we have published
about sendmail.

<LI><P>TFTP file access<BR>
See CERT advisory <A HREF="http://www.cert.org/advisories/CA-91.18.Active.Internet.tftp.Attacks.html">CA-91.18</A> for security measures that address TFTP access
problems. In addition, <A HREF="http://www.cert.org/advisories/CA-91.19.AIX.TFTP.Daemon.vulnerability.html">CA-91.19</A> contains information for IBM AIX users.

<LI><P>Remote shell access<BR>
We recommend that you comment out rshd in the file /etc/inetd.conf or protect
it with a TCP wrapper. A TCP/IP wrapper program is available from 
<BR><A HREF="ftp://ftp.cert.org/pub/tools/tcp_wrappers/">ftp://ftp.cert.org/pub/tools/tcp_wrappers/</A>

<LI><P>Unrestricted X server access<BR>
We recommend filtering X at your firewall. Additional advice about packet
filtering is available by anonymous FTP from
<BR><A HREF="ftp://ftp.cert.org/pub/tech_tips/packet_filtering">ftp://ftp.cert.org/pub/tech_tips/packet_filtering</A>

<LI><P>Writable FTP home directory
<BR>See CERT advisory <A HREF="http://www.cert.org/advisories/CA-93.10.anonymous.FTP.activity.html">CA-93.10</A>.
<BR>Guidance on anonymous FTP configuration is also available from
<BR> <A HREF="ftp://ftp.cert.org/pub/tech_tips/anonymous_ftp_config">ftp://ftp.cert.org/pub/tech_tips/anonymous_ftp_config</A>

<LI><P>wu-ftpd vulnerability
<BR>See <A HREF="http://www.cert.org/advisories/CA-93.06.wuarchive.ftpd.vulnerability.html">CA-93.06</A> and <A HREF="http://www.cert.org/advisories/CA-94.07.wuarchive.ftpd.trojan.horse.html">CA-94.07</A> for more information about ftpd.

<LI><P>Unrestricted dial-out modem available via TCP.
<BR>Place modems behind a firewall or put password or other extra
authentication on them (such as S/Key or one-time passwords). For information
on one-time passwords, see CERT advisory <A HREF="http://www.cert.org/advisories/CA-94.01.ongoing.network.monitoring.attacks.html">CA-94.01</A>, Appendix B.


<P><B>Note:</B> In addition to our FTP archive at ftp.cert.org, CERT documents
are available from the following sites, and others which you can locate
by using archie:

<A HREF="ftp://coast.cs.purdue.edu/pub/mirrors/cert.org/cert_advisories">ftp://coast.cs.purdue.edu/pub/mirrors/cert.org/cert_advisories</A><BR>
<A HREF="ftp://unix.hensa.ac.uk/pub/uunet/doc/security/cert_advisories">ftp://unix.hensa.ac.uk/pub/uunet/doc/security/cert_advisories</A><BR>
<A HREF="ftp://ftp.luth.se/pub/misc/cert/cert_advisories">ftp://ftp.luth.se/pub/misc/cert/cert_advisories</A><BR>
<A HREF="ftp://ftp.switch.ch/network/security/cert_advisories">ftp://ftp.switch.ch/network/security/cert_advisories</A><BR>
<A HREF="ftp://corton.inria.fr/CERT/cert_advisories">ftp://corton.inria.fr/CERT/cert_advisories</A><BR>
<A HREF="ftp://ftp.inria.fr/network/cert_advisories">ftp://ftp.inria.fr/network/cert_advisories</A><BR>
<A HREF="ftp://nic.nordu.net/networking/security/cert_advisories">ftp://nic.nordu.net/networking/security/cert_advisories</A>

<H4>5. Currently Available Tools</H4>

The following tools are freely available now and can help you improve your
site's security before SATAN is released.

<P>COPS and ISS can be used to check for vulnerabilities and configuration

<P>COPS is available from <A HREF="ftp://ftp.cert.org/pub/tools/cops/">ftp//ftp.cert.org:/pub/tools/cops/*</A>

<P>ISS is available from
<BR><A HREF="ftp://ftp.uu.net/usenet/comp.sources.misc/volume39/iss">ftp://ftp.uu.net/usenet/comp.sources.misc/volume39/iss</A>
CERT advisory <A HREF="http://www.cert.org/advisories/CA-93.14.Internet.Security.Scanner.html">CA-93.14</A> contains information about ISS.

<P>TCP wrappers can provide access control and flexible logging to most
network services. These features can help you prevent and detect network
attacks. This software is available by anonymous FTP from

<P><A HREF="ftp://ftp.cert.org/pub/tools/tcp_wrappers/">ftp://ftp.cert.org/pub/tools/tcp_wrappers/*</A>

<P>The TAMU security package includes tools to check for vulnerabilities
and system configuration weaknesses, and it provides logging and filtering
of network services. This software is available by anonymous FTP from

<P><A HREF="ftp://net.tamu.edu/pub/security/TAMU/*">ftp://net.tamu.edu/pub/security/TAMU/*</A>

<P>The Swatch log file monitor allows you to identify patterns in log
file entries and associate them with actions. This tool is available from

<P><A HREF="ftp://ee.stanford.edu/pub/sources/swatch.tar.Z">ftp://ee.stanford.edu/pub/sources/swatch.tar.Z</A>

<H4>6. Detecting Probes</H4>

One indication of attacks by SATAN, and other tools, is evidence of a heavy
scan of a range of ports and services in a relatively short time. Many
UNIX network daemons do not provide sufficient logging to determine if
SATAN is probing the system. TCP wrappers, the TAMU tools, and Swatch can
provide the logging you need.

<P>New tools are becoming available on the network to help you detect
probes, but the CERT staff has not evaluated them.

<P>Although detection tools can be helpful, keep in mind that their effectiveness
depends on the nature and availability of your logs and that the tools
may become less effective as SATAN is modified. The most important thing
you can do is take preventive action to secure your systems.

<H4>7. Using SATAN</H4>

Running SATAN on your systems will provide you with the same information
an attacker would obtain, allowing you to correct vulnerabilities. If you
choose to run SATAN, we urge you to read the documentation carefully. Also,
note the following:

<LI>It is easy to accidentally probe systems you did not intend to. If this
occurs, the probed site may view the probe(s) as an attack on their system(s).</LI>

<LI><P>Take special care in setting up your configuration file, and in selecting
the probe level when you run SATAN.</LI>

<LI><P>Explicitly bound the scope of your probes when you run SATAN. Under "SATAN
Configuration Management," explicitly limit probes to specific hosts and
exclude specific hosts.</LI>

<LI><P>When you run SATAN, ensure that other users do not have read access to
your SATAN directory.</LI>

<LI><P>In some cases, SATAN points to CERT advisories. If the link does not work
for you, try getting the advisories by anonymous FTP.</LI>

<LI><P>Install all relevant security patches for the system on which you will
run SATAN.</LI>

<LI><P>Ensure that the SATAN directory tree cannot be read by users other than

<LI><P>Execute SATAN only from the console of the system on which it is installed
(e.g., do not run SATAN from an X terminal, from a diskless workstation,
or from a remote host).</LI>

<LI><P>Ensure that the SATAN directory tree is not NFS-mounted from a remote system.</LI>

<LI><P>It is best to run SATAN from a system that does not support multiple users.</LI>

<H4>8. Getting more information about SATAN</H4>

The SATAN authors report that SATAN 1.1.1 is available from many sites,
<A HREF="ftp://ftp.win.tue.nl/pub/security/satan-1.1.1.tar.Z">ftp://ftp.win.tue.nl/pub/security/satan-1.1.1.tar.Z</A><BR>
<A HREF="ftp://ftp.win.tue.nl/pub/security/satan-1.1.1.README">ftp://ftp.win.tue.nl/pub/security/satan-1.1.1.README</A><BR>
<A HREF="ftp://ftp.win.tue.nl/pub/security/satan_doc.tar.Z">ftp://ftp.win.tue.nl/pub/security/satan_doc.tar.Z</A><BR>
<A HREF="ftp://ftp.win.tue.nl/pub/security/satan_doc.README">ftp://ftp.win.tue.nl/pub/security/satan_doc.README</A><BR>

<P>To get a current list of sites, send mail to:

<UL><A HREF="mailto:majordomo@wzv.win.tue.nl">majordomo@wzv.win.tue.nl</A></UL>

<P>and put in the body of your message

<UL>get satan mirror-sites</UL>

<P>You can also use archie to locate sites that have SATAN.

<P>MD5 checksums for SATAN:
satan-1.1.1.README = 3f935e595ab85ee28b327237f1d55287
<BR>satan-1.1.1.tar.Z = de2d3d38196ba6638b5d7f37ca8c54d7
<BR>satan-1.1.1.tar.Z.asc = a9261070885560ec11e6cc1fe0622243 
<BR>satan_doc.README = 4ebe05abc3268493cdea0da786bc9589
<BR>satan_doc.tar.Z = 951d8bfca033eeb483a004a4f801f99a
<BR>satan_doc.tar.Z.asc = 3216053386f72347956f2f91d6c1cb7c

<P>Also available is "Improving the Security of Your Site by Breaking
Into It" (admin-guide-to-cracking.101), a 1993 paper in which the authors
give their rationale for creating SATAN.

<P><HR>The CERT Coordination Center staff thanks Dan Farmer and Wieste Venema
for the the opportunity to examine pre-release versions of SATAN. We also
appreciate the interaction with the response teams at AUSCERT, CIAC, and
DFN-CERT, and feedback from Eric Allman.


Note to users of LINUX SATAN: There was a posting to USENET that a
Trojan horse was introduced into a version of LINUX SATAN binaries archived
on ftp.epinet.com. CERT staff have not verified that this Trojan horse
exists; however, if you are using LINUX SATAN and believe your version
may be compromised, we suggest you obtain additional information from

<P><A HREF="ftp://ftp.epinet.com/pub/linux/security">ftp://ftp.epinet.com/pub/linux/security</A>


<!--#include virtual="/include/footer_nocopyright.html" -->
<P>Copyright 1995, 1996 Carnegie Mellon University.</P>


Revision History
Sep. 23, 1997  Updated copyright statement
Aug. 30, 1996  Information previously in the README was inserted into
               the advisory. Updated tech tip references.
Apr. 11, 1995  Updated information based on SATAN 1.1.1 (original advisory
               was based on beta version 0.51):
                 Introduction - added reference to CA-95.07a 
                 Sec. 4 - added information on SATAN probe for unrestricted 
                 Sec. 6 - added a note on tools for detecting probes 
                 Sec. 7 - added five additional precautions
                 Sec. 8 - where to get a copy of SATAN
                          checksums for SATAN and documentation 
                          where to send comments about SATAN
Apr. 11, 1995  Sec. 3 - pathnames corrected in Sec. 3
               Sec. 4-5 - colons noted in (and subsequently removed from) URLs
Apr. 11, 1995  Updates section - added a note on LINUX SATAN