-----BEGIN PGP SIGNED MESSAGE----- - --------------------------------------------------------------------------- CERT Summary CS-95:01 July 26, 1995 As part of our ongoing efforts to disseminate timely information about Internet security issues, the CERT Coordination Center is pleased to announce the CERT Summary. CERT Summary will be distributed periodically to call attention to the types of attacks currently being reported to the CERT Coordination Center. The summary will include pointers to sources of information for dealing with the problems. - --------------------------------------------------------------------------- Recent Activity The majority of incidents reported to the CERT Coordination Center in recent weeks fall into three categories: 1. IP Spoofing: We have seen a surge in IP spoofing. In recent weeks, we have received more than 170 reports of IP spoofing attacks or probes, many of them resulting in a successful break in. Several sites believed incorrectly that they were blocking such packets. Others planned to block them but hadn't yet done so. We urge you to take the time to review CERT Advisory CA-95:01, "IP Spoofing Attacks and Hijacked Terminal Connections," which has details on this type of attack and how to prevent it. Vulnerability to IP spoofing attacks is NOT limited to any specific router or OS vendor. This advisory is available from ftp://info.cert.org/pub/cert_advisories/CA-95:01.IP.spoofing 2. Packet Sniffers: We receive new reports daily that describe sniffers installed on compromised hosts. These sniffers, which are used to collect account names and passwords, are frequently installed using a kit. Further information on packet sniffers is available from ftp://info.cert.org/pub/cert_advisories/CA-94:01.network.monitoring.attacks Once root is compromised on a system, the sniffer kit can be activated to collect account names and passwords. Note that even if sniffing capabilities are disabled by recompiling and rebooting the kernel, we have received reports of intruders re-enabling these capabilities by recompiling and rebooting systems. Pay particular attention to every system reboot. In the attacks that we have seen, intruders frequently install (as root) Trojan horse system software that is available with the sniffer kit. Further information on the Trojan horses that we have seen is available from ftp://info.cert.org/pub/cert_advisories/CA-94:05.MD5.checksums 3. NFS Attacks: We have seen a large increase in the number of attacks and probes against weaknesses within NFS. Again, many of these are successful. Programs to automate such attacks have become widespread. Please review CERT Advisory CA-94:15, "NFS Vulnerabilities," available in ftp://info.cert.org/pub/cert_advisories/CA-94:15.NFS.Vulnerabilities A successful attack usually results in the intruders gaining root access. Intruders have been targeting machines with vendor-licensed source code. They appear to be in search of the code for system software with the view to creating and installing copies containing Trojan horses on compromised systems. If you manage systems that contain vendor-licensed source code, pay particular attention to the "Security Measures" section of the advisory. - ------------------------- New Trojan Horse Programs Once root has been compromised on a system, we are finding new Trojan horses installed in the inetd and in.rexecd daemons. These Trojan horses allow an intruder to gain access at a later time, bypassing most firewall and TCP wrapper configurations. Do not rely on checksums determined by the sum(1) program because intruders are creating files whose checksums match those of the vendor-distributed versions. Do not rely on time stamps of these files either because intruders are setting these to previous values as well. We recommend that you use a known clean version of cmp(1) to make a direct comparison of the binaries and the appropriate distribution media. Alternatively, you can check the MD5 results on suspect binaries against a list of MD5 checksums from known good binaries. Ask your vendor to make MD5 checksums available for their distribution binaries. You can also consult the following for some additional information on MD5: ftp://info.cert.org/pub/cert_advisories/CA-94:05.MD5.checksums In addition, tools such as Tripwire can archive MD5 checksums of known good binaries when used immediately after a system installation. If you use Tripwire, you should regularly maintain the checksums on removable or read-only media. For more details on Tripwire and MD5, please see: ftp://info.cert.org/pub/tech_tips/intruder_detection_checklist We are also seeing Trojan horses introduced into shared object libraries. Examples are /usr/lib/libc.so.* and /usr/kvm/libkvm.so.* on SunOS-based machines. Although we have only received reports of SunOS-based machines being altered, the techniques used by intruders are applicable to other systems that use shared object libraries. These libraries are being modified so that the presence of certain directories and processes cannot be detected with vendor-provided programs or public domain programs built to use shared object libraries. This means that ANY program using these shared libraries will act in the manner described by the intruder without the intruder necessarily having to modify the program itself. The Trojan horse daemons previously described typically become "invisible" to programs such as ps once the kvm shared object library has been modified. Similarly, the directories used by intruders for building these daemons are "invisible" once the libc shared object library has been modified. Again, do not rely on checksums using sum(1) or time stamps to detect altered files. Use a known clean version of cmp(1) or a strong checksum technique such as MD5 to verify your files against the appropriate distribution. - --------------------------------------------------------------------------- If you believe that your system has been compromised, contact the CERT Coordination Center or your representative in the Forum of Incident Response and Security Teams (FIRST). If you wish to send sensitive incident or vulnerability information to CERT staff by electronic mail, we strongly advise that the e-mail be encrypted. The CERT Coordination Center can support a shared DES key, PGP (public key available via anonymous FTP on info.cert.org), or PEM (contact CERT staff for details). Internet e-mail: cert@cert.org Telephone: +1 412-268-7090 (24-hour hotline) CERT personnel answer 8:30 a.m.-5:00 p.m. EST(GMT-5)/EDT(GMT-4), and are on call for emergencies during other hours. Fax: +1 412-268-6989 Postal address: CERT Coordination Center Software Engineering Institute Carnegie Mellon University Pittsburgh, PA 15213-3890 USA CERT advisories and bulletins are posted on the USENET news group comp.security.announce. If you would like to have future advisories and bulletins mailed to you or to a mail exploder at your site, please send mail to cert-advisory-request@cert.org. Past CERT publications, information about FIRST representatives, and other information related to computer security are available by anonymous FTP from info.cert.org. - --------------------------------------------------------------------------- Copyright 1995 Carnegie Mellon University This material may be reproduced and distributed without permission provided it is used for noncommercial purposes and the copyright statement is included. CERT is a service mark of Carnegie Mellon University. -----BEGIN PGP SIGNATURE----- Version: 2.6.2 iQCVAwUBMhCoTHVP+x0t4w7BAQF7BgP9EcV6BBuZuqgauwcceQH6/xNNYU0tv5v6 SOyZ8plPjdDRNLTObsepEvnnl3XnsYr0DuuQGjCqpLEP7JP1clNIIgiJ+aL7a1UD T99WUtj2TRmUhs27MAWLZi1C7XVboaZp+9Dn9uReHnk9cX6SlYJZF4SOcZVOOjS9 83kBdrh/HMw= =FzmU -----END PGP SIGNATURE----- -----BEGIN PGP SIGNED MESSAGE----- - --------------------------------------------------------------------------- CERT Summary CS-95:02 September 26, 1995 The CERT Coordination Center periodically issues the CERT Summary to draw attention to the types of attacks currently being reported to our incident response staff. The summary includes pointers to sources of information for dealing with the problems. Starting with this summary, we will also list new or updated files that are available for anonymous FTP from ftp://info.cert.org Past CERT Summaries are available from ftp://info.cert.org/pub/cert_summaries - --------------------------------------------------------------------------- Recent Activity - --------------- Since the July CERT Summary, we have seen these continuing trends in incidents reported to us: 1. Sendmail Attacks We receive several reports each week of attacks through sendmail, with intruders using a variety of techniques. Most of the attacks are aimed at gaining privileged access to the victim machine. To combat these threats, we encourage sites to take the appropriate steps outlined in the following: ftp://info.cert.org/pub/cert_advisories/CA-95:11.sun.sendmail-oR.vul ftp://info.cert.org/pub/cert_advisories/CA-95:08.sendmail.v.5.vulnerability A number of sites have reported some confusion on the need to continue using the sendmail restricted shell program (smrsh). You need to run the smrsh tool in conjunction with the most recently patched version of sendmail for your system. Information on the smrsh tool can be obtained from these places in ftp://info.cert.org/pub/ tools/sendmail/smrsh/ cert_advisories/CA-93:16.sendmail.vulnerability cert_advisories/CA-93:16a.sendmail.vulnerability.supplement cert_advisories/CA-95:11.sun.sendmail-oR.vul The smrsh program can be obtained from ftp://info.cert.org/pub/tools/smrsh/ It is included in the sendmail 8.7 distribution. 2. Network Scanning Several incidents have recently been reported in which intruders scan a large address range using the Internet Security Scanner (ISS). As described in CERT advisory CA-93:14, this tool interrogates all computers within a specified IP address range, determining the security posture of each with respect to several common system vulnerabilities. Intruders have used the information gathered from these scans to compromise sites. We are aware of many systems that have suffered a root compromise as a result of information intruders obtained from ISS scans. You may wish to run ISS against your own site in accordance with your organization's policies and procedures. ISS is available from ftp://info.cert.org/pub/tools/iss/iss13.tar We encourage you to take relevant steps outlined in these documents: ftp://info.cert.org/pub/cert_advisories/CA-93:14.Internet.Security.Scanner ftp://info.cert.org/pub/tech_tips/intruder_detection_checklist ftp://info.cert.org/pub/tech_tips/packet_filtering 3. Exploitation of rlogin and rsh We have received some reports about the continued exploitation of a vulnerability in rlogin and rsh affecting IBM AIX 3 systems and Linux systems. This is not a new vulnerability, but it continues to exist. Sites have reported encountering some Linux distributions that contain this vulnerability. Information on this vulnerability and available solutions can be obtained from ftp://info.cert.org/pub/cert_advisories/CA-94:09.bin.login.vulnerability 4. Packet Sniffers We continue to receive new incident reports daily about sniffers on compromised hosts. These sniffers, used to collect account names and passwords, are frequently installed using a kit. In some cases, the packet sniffer was found to have been running for months. Occasionally, sites had been explicitly warned of the possibility of such a compromise, but the sniffer activity continued because the site did not address the problem in the comprehensive manner that we suggest in our security documents. Further information on packet sniffers is available from ftp://info.cert.org/pub/cert_advisories/CA-94:01.network.monitoring.attacks Information about detecting sniffers using cpm is included in the advisory. What's New in the CERT FTP Archive - ---------------------------------- We have made the following changes since June 1, 1995. * New Additions: ftp://info.cert.org/pub/ incident.reporting.form (the form you should fill out when reporting an incident to our staff) ftp://info.cert.org/pub/cert_advisories/ CA-95:08.sendmail.v.5.vulnerability CA-95:09.Solaris.ps.vul CA-95:10.ghostscript CA-95:11.sun.sendmail-oR.vul ftp://info.cert.org/pub/cert_bulletins/ VB-95:05.osf (OSF/DCE security hole) VB-95:06.cisco (vulnerability in Cisco's IOS software) ftp://info.cert.org/pub/tech_tips/ AUSCERT_checklist_1.0 (UNIX checklist developed by the Australian Emergency Response Team) * Updated Files ftp://info.cert.org/pub/cert_advisories/ CA-93:14 (Internet Security Scanner) CA-94:01 (network monitoring) CA-94:02 (SunOS rpc mountd vulnerability) CA-94:05 (md5) CA-94:11 (majordomo) CA-95:01 (IP spoofing and hijacked terminal connections) CA-95:02 (binmail vulnerabilities) CA-95:05 (sendmail - several vulnerabilities) CA-95:08 (sendmail version 5 and IDA sendmail) CA-95:09 (Solaris ps) CA-95:11 (Sun sendmail -oR vulnerability) We have begun adding a note reminding readers to check with vendors for current checksum values. After we publish checksums in advisories, files and checksums are sometimes updated at individual locations. * Other Changes: As we will no longer be keeping the lsof directory current, the directory and its files have been removed from our FTP site. The current version of lsof is available from ftp://vic.cc.purdue.edu/pub/tools/unix/lsof - --------------------------------------------------------------------------- How to Contact the CERT Coordination Center Email cert@cert.org Phone +1 412-268-7090 (24-hour hotline) CERT personnel answer 8:30-5:00 p.m. EST (GMT-5)/EDT(GMT-4), and are on call for emergencies during other hours. Fax +1 412-268-6989 Postal address CERT Coordination Center Software Engineering Institute Carnegie Mellon University Pittsburgh PA 15213-3890 To be added to our mailing list for CERT advisories and bulletins, send your email address to cert-advisory-request@cert.org CERT advisories and bulletins are posted on the USENET news group comp.security.announce If you wish to send sensitive incident or vulnerability information to CERT staff by electronic mail, we strongly advise that the email be encrypted. We can support a shared DES key, PGP, or PEM (contact CERT staff for details). Location of CERT PGP key ftp://info.cert.org/pub/CERT.PGP_key - --------------------------------------------------------------------------- Copyright 1995 Carnegie Mellon University This material may be reproduced and distributed without permission provided it is used for noncommercial purposes and credit is given to the CERT Coordination Center. CERT is a service mark of Carnegie Mellon University. -----BEGIN PGP SIGNATURE----- Version: 2.6.2 iQCVAwUBMhCqx3VP+x0t4w7BAQHSxgP/Qo1eIkenmJLR/vx55MgZdLgIWExssdUT GGtgM9ho3W8wVJh44NGaPh5dvjmox6DcWlmAkQpyK4Vo0yZVe2a+rMQoHh+4D5pP lMFPzx9Bhp8P5kPmIuIjLcjJE3fHYDNoRMrlugdYiJUaT/HL6tu2kPPOEHQaOPJF 6qS1qimE1Bw= =M5N8 -----END PGP SIGNATURE----- -----BEGIN PGP SIGNED MESSAGE----- - --------------------------------------------------------------------------- CERT Summary CS-95:03 November 28, 1995 The CERT Coordination Center periodically issues the CERT Summary to draw attention to the types of attacks currently being reported to our incident response staff. The summary includes pointers to sources of information for dealing with the problems. We also list new or updated files that are available for anonymous FTP from ftp://info.cert.org Past CERT Summaries are available from ftp://info.cert.org/pub/cert_summaries - --------------------------------------------------------------------------- Recent Activity - --------------- Since the September CERT Summary, we have seen these continuing trends in incidents reported to us. The majority of reported incidents fit into four categories: 1. Packet Sniffers We continue to see daily incident reports about intruders who have installed sniffers on compromised systems. These sniffers, used to collect account names and passwords, are frequently installed with a kit that includes Trojan horse binaries. The Trojan horse binaries hide the sniffer activity on the systems on which they are installed. For further information and methods for detecting packet sniffers and Trojan horses, see the following files: ftp://info.cert.org/pub/cert_advisories/CA-94:01.network.monitoring.attacks ftp://info.cert.org/pub/cert_advisories/CA-94:05.MD5.checksum 2. Exploitation of SGI lp Vulnerability The vulnerability described in CERT advisory, CA:95:15 "SGI lp Vulnerability" continues to be exploited, though we have seen a decline in the number of reports since the advisory was released on November 8. Intruders gain unauthorized access to Silicon Graphics, Inc. (SGI) IRIX systems through a passwordless lp account; they use this initial access to leverage additional privileges on the compromised system. As distributed by SGI, the lp account (as well as other accounts), has no password on a newly installed system. This fact is addressed in the documentation that SGI distributes with their systems: "IRIX Advanced Site and Server Administrative Guide" (see the chapter on System Security). More information on this vulnerability and how it can be addressed can be obtained from ftp://info.cert.org/pub/cert_advisories/CA-95:15.SGI.lp.vul 3. Network Scanning We continue to receive several reports each week of intruders using the Internet Security Scanner (ISS) to scan both individual hosts and large IP address ranges. The ISS tool, which is described in CERT advisory CA-93:14 "Internet Security Scanner", interrogates all computers within a specified IP address range, determining the security posture of each with respect to several common system vulnerabilities. Intruders use the information gathered from such scans to gain unauthorized access to the scanned sites. As part of a defensive strategy, you may want to consider running ISS against your own site (in accordance with your organization's policies and procedures) to identify any possible system weaknesses or vulnerabilities, taking steps to implement security fixes that may be necessary. ISS is available from ftp://info.cert.org/pub/tools/iss/iss13.tar More information about the ISS tool and steps for protecting your site are outlined in the following documents: ftp://info.cert.org/pub/cert_advisories/CA-93:14.Internet.Security.Scanner ftp://info.cert.org/pub/tech_tips/intruder_detection_checklist ftp://info.cert.org/pub/tech_tips/packet_filtering 4. Sendmail Attacks New reports of intruders attacking sites through sendmail vulnerabilities are continuing to arrive daily, although most reports indicate the attacks have failed. The types of attacks are varied, but most are aimed at gaining privileged access to the victim machine. We encourage sites to combat these threats by taking the appropriate steps, described in the following documents: ftp://info.cert.org/pub/cert_advisories/CA-95:05.sendmail.vulnerabilities ftp://info.cert.org/pub/cert_advisories/CA-95:08.sendmail.v.5.vulnerability ftp://info.cert.org/pub/cert_advisories/CA-95:11.sun.sendmail-oR.vul What's New in the CERT FTP Archive - ---------------------------------- We have made the following changes since the last CERT Summary (September 26, 1995). * New Additions ftp://info.cert.org/pub/cert_advisories/ CA-95:12.sun.loadmodule.vul CA-95:13.syslog.vul CA-95:14.Telnetd_Environment_Vulnerability CA-95:15.SGI.lp.vul ftp://info.cert.org/pub/cert_bulletins/ VB-95:07.abell (lsof) VB-95-08.X_Authentication_Vul ftp://info.cert.org/pub/tools/sendmail sendmail/sendmail.8.7.1.tar sendmail/sendmail.8.7.1.tar.Z * Updated Files ftp://info.cert.org/pub/cert_advisories/ CA-93:16a (sendmail - note to use smrsh with all versions) CA-95:05 (sendmail - date of Digital Equipment's patch) CA-95:08 (sendmail - note to use smrsh with all versions) CA-95:10 (ghostscript - patches and explanations) CA-95:13 (syslog - information from vendors) CA-95:14 (telnetd - information from vendors; correction to compilation example) ftp://info.cert.org/pub/tools/cops README (more recent email address for COPS author Dan Farmer) - --------------------------------------------------------------------------- How to Contact the CERT Coordination Center Email cert@cert.org Phone +1 412-268-7090 (24-hour hotline) CERT personnel answer 8:30-5:00 p.m. EST (GMT-5)/EDT(GMT-4), and are on call for emergencies during other hours. Fax +1 412-268-6989 Postal address CERT Coordination Center Software Engineering Institute Carnegie Mellon University Pittsburgh PA 15213-3890 To be added to our mailing list for CERT advisories and bulletins, send your email address to cert-advisory-request@cert.org CERT advisories and bulletins are posted on the USENET news group comp.security.announce If you wish to send sensitive incident or vulnerability information to CERT staff by electronic mail, we strongly advise that the email be encrypted. We can support a shared DES key, PGP, or PEM (contact CERT staff for details). Location of CERT PGP key ftp://info.cert.org/pub/CERT.PGP_key - --------------------------------------------------------------------------- Copyright 1995 Carnegie Mellon University This material may be reproduced and distributed without permission provided it is used for noncommercial purposes and credit is given to the CERT Coordination Center. CERT is a service mark of Carnegie Mellon University. -----BEGIN PGP SIGNATURE----- Version: 2.6.2 iQCVAwUBMhCrZnVP+x0t4w7BAQGTsgP6A+QyYJuzdqS3wIUwBR34lQ0OFmDd3PV/ 9wO5X8o2zxbACFo8Ps9jc9gSwhs3J/uEIYhbr5vPOHwq9Rpkk7C2sTYQn9r8FN3H TywMkt3QSwncSYp5LdgHiR3J230iWtgIBaePIsjVGp2b6RRPjSDrmrudIz8ncOup JfhrIvC7NUw= =xGeL -----END PGP SIGNATURE-----