CERT Summary CS-99-03

Each quarter, the CERTŪ Coordination Center (CERT/CC) issues the CERT summary to draw attention to the types of attacks reported to our incident response team, as well as other noteworthy incident and vulnerability information. The summary includes pointers to sources of information for dealing with the problems.

Past CERT summaries are available from http://www.cert.org/summaries/

On October 4, 1999, the current PGP key for the CERT/CC will be replaced with a new PGP key. For more information, see

http://www.cert.org/pgp/newpgp.html

The CERT/CC Current Activity web page is a regularly updated summary of the most frequent, high-impact types of security incidents and vulnerabilities currently being reported to the CERT/CC. It is available from

http://www.cert.org/current/current_activity.html The information on the Current Activity page will be reviewed and updated as reporting trends change.

Since the last CERT summary, issued in May 1999 (CS-99-02), we have noted several vulnerabilities in RPC services, and we have analyzed and published information regarding the ExploreZip worm. We also continue to see widespread scans for known vulnerabilites.

Protect your systems. Use current software versions, install patches as they become available, and update your scanning tools and anti-virus software with the latest virus signatures or definitions. Be cautious of unsolicited documents or executable programs received in electronic mail. Be wary of software that comes from untrusted sources.

1. RPC Vulnerabilities

• rpc.cmsd
  Remote and local users can execute arbitrary code with the privileges of the rpc.cmsd daemon, typically root. This vulnerability is being exploited in a significant number of incidents reported to the CERT/CC. For more information see

          CERT Incident Note 99-04
              http://www.cert.org/incident_notes/IN-99-04.html
              CERT Advisory CA-99-08
              http://www.cert.org/advisories/CA-99-08-cmsd.html
  

• statd and automoutd
  Vulnerabilities in these two services are being used together by intruders to gain access to vulnerable systems. The first vulnerability is in rpc.statd, a program used to communicate state changes among NFS clients and servers. The second vulnerability is in automountd, a program used to automatically mount certain types of file systems. The vulnerability in rpc.statd may allow a remote intruder to call arbitrary RPC services with the privileges of the rpc.statd process, typically root. The vulnerablility in automountd may allow a local intruder to execute arbitrary commands with the privileges of the automountd service. By combining attacks exploiting these two vulnerabilities, a remote intruder is able to execute arbitrary commands with the privileges of the automountd service. For more information see
  

          CERT Incident Note 99-04
              http://www.cert.org/incident_notes/IN-99-04.html
              CERT Advisory CA-99-05
              http://www.cert.org/advisories/CA-99-05-statd-automountd.html
  

• ttbserverd
  The ToolTalk database server (rpc.ttdbserverd) is an ONC RPC service that manages objects needed for the operation of the ToolTalk service. ToolTalk-enabled processes communicate with each other using RPC calls to this program, which runs on each ToolTalk-enabled host. This program is a standard component of CDE (Common Desktop Environment), which is a standard component of many commercial Unix operating systems.
  Due to an implementation fault in rpc.ttdbserverd, it is possible for a malicious remote client to formulate an RPC message that can lead to a buffer overflow. This buffer overflow can result in an attacker gaining total control of the ttdbserver process. An intruder may be able to use this control to gain root-level privileges.
  

          CERT Incident Note 99-04
              http://www.cert.org/incident_notes/IN-99-04.html
              CERT Advisory CA-98-11
              http://www.cert.org/advisories/CA-98.11.tooltalk.html
  

2. Virus and Trojan Horse Activity

We continue to see reports of virus activity. Current versions of anti-virus software can help to protect your systems from these viruses.

It is important to take great caution with any email or Usenet attachments that contain executable content. If you receive a message containing attachments, scan the message file with anti-virus software before you open or run the file. Doing this does not guarantee that the contents of the file are safe, but it lowers your risk of virus infection by checking for viruses and Trojan horses that your scanning software can detect.

ExploreZip.exe
The ExploreZip program is a Trojan horse affecting Windows 95/98/NT systems. It modifies system files and destroys files. For ExploreZip to work, a person must open or run an infected email attachment, which allows the program to install a copy of itself on the victim's computer and enables further propagation. ExploreZip may also behave as a worm, propagating to other network machines without human interaction. For more information see

        CERT Advisory CA-99-06 ExploreZip Trojan Horse Program
            http://www.cert.org/advisories/CA-99-06-explorezip.html
            CERT Advisory CA-99-02 Trojan Horses
            http://www.cert.org/advisories/CA-99-02-Trojan-Horses.html

3. Continued Widespread Scans
We are still receiving daily reports of intruders using tools to scan networks for multiple vulnerabilities. Intruder scanning tools continue to become more sophisticated, varying from scripted tools and stealth scanning techniques to a tool that incorporates probes for known vulnerabilities, remote operating system identification, and automated exploitation attempts. For more information, see

"sscan" Scanning Tool

            http://www.cert.org/incident_notes/IN-99-01.html
            Automated Scanning and Exploitation
            http://www.cert.org/incident_notes/IN-98-06.html
            Probes with Spoofed IP Addresses
            http://www.cert.org/incident_notes/IN-98-05.html
            Advanced Scanning
            http://www.cert.org/incident_notes/IN-98.04.html
            New Tools Used for Widespread Scans
            http://www.cert.org/incident_notes/IN-98.02.html

The most frequent reports involve well-known vulnerabilities in mountd, IMAP, POP3, and several RPC services. These services are installed and enabled by default in some operating systems. See the following advisories for more information:

        sunrpc (TCP port 111) and mountd (635)
            http://www.cert.org/advisories/CA-98.12.mountd.html
            http://www.cert.org/incident_notes/IN-99-04.html
            IMAP (TCP port 143)
            http://www.cert.org/advisories/CA-98.09.imapd.html
            POP3 (TCP port 110)
            http://www.cert.org/advisories/CA-98.08.qpopper_vul.html
            DNS (TCP port 53 [domain])
            http://www.cert.org/advisories/CA-98.05.bind_problems.html
            http://www.cert.org/advisories/CA-97.22.bind.html

These scans involve known vulnerabilities for which patches are available. Protect your systems by making sure that they are properly secured.

Since the last CERT summary, we have developed new and updated

• * Advisories
• * Courses
• * Incident notes
• * Security improvement modules
• * Technical reports
• * Tech tips
• * Virus resources

There are descriptions of these documents and links to them on our "What's New" web page at

http://www.cert.org/nav/whatsnew.html

 http://www.cert.org/summaries/CS-99-03.html

CERT/CC Contact Information

 Email: cert@cert.org
          Phone: +1 412-268-7090 (24-hour hotline)
          Fax: +1 412-268-6989
          Postal address:
          CERTŪ Coordination Center
          Software Engineering Institute
          Carnegie Mellon University
          Pittsburgh PA 15213-3890
          U.S.A.
          

CERT personnel answer the hotline 08:00-20:00 EST(GMT-5) / EDT(GMT-4) Monday through Friday; they are on call for emergencies during other hours, on U.S. holidays, and on weekends.

Using encryption

We strongly urge you to encrypt sensitive information sent by email. Our public PGP key is available from

 http://www.cert.org/CERT_PGP.key

If you prefer to use DES, please call the CERT hotline for more information.

Getting security information

CERT publications and other security information are available from our web site

http://www.cert.org/

To be added to our mailing list for advisories and bulletins, send email to cert-advisory-request@cert.org and include SUBSCRIBE your-email-address in the subject of your message.

Copyright 1999 Carnegie Mellon University. Conditions for use, disclaimers, and sponsorship information can be found in

 http://www.cert.org/legal_stuff.html

* "CERT" and "CERT Coordination Center" are registered in the U.S. Patent and Trademark Office.

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