-----BEGIN PGP SIGNED MESSAGE----- __________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Web Security May 17, 1999 21:00 GMT Number J-042 ______________________________________________________________________________ PROBLEM: Public web servers continue to be attractive targets for hackers seeking to embarrass organizations or promote a political agenda. Good security practices can protect your site from the risks such compromises create. PLATFORM: Any Unix platform or NT system being used as a web server. DAMAGE: Damage can be anything from a denial-of-service attack, the placement of pornographic material, the posting of political messages, or the deletion of files or the placement of malicious software. SOLUTION: Follow known best practices and apply software patches as soon as they are announced by your incident response team or your vendor. ______________________________________________________________________________ VULNERABILITY Public web sites are hacked on an almost daily basis; the ASSESSMENT: threat that your site could be compromised is real. ______________________________________________________________________________ BEST PRACTICES IN MANAGING WORLD WIDE WEB SERVER SECURITY: 1. Place your web server(s) in a DMZ. Set your firewall to drop connections to your web server on all ports but http (port 80) or https (port 443). 2. Remove all unneeded services from your web server, keeping FTP (but only if you need it) and a secure login capability such as secure shell. An unneeded service can become an avenue of attack. 3. Disallow all remote administration unless it is done using a one-time password or an encrypted link. 4. Limit the number of persons having administrator or root level access. 5. Log all user activity and maintain those logs either in an encrypted form on the web server or store them on a separate machine on your Intranet. 6. Monitor system logs regularly for any suspicious activity. Install some trap macros to watch for attacks on the server (such as the PHF attack). Create macros that run every hour or so that would check the integrity of passwd and other critical files. When the macros detect a change, they should send an e-mail to the system manager. 7. Remove ALL unnecessary files such as phf from the scripts directory /cgi-bin. 8. Remove the "default" document trees that are shipped with Web servers such as IIS and ExAir. 9. Apply all relevant security patches as soon as they are announced. 10. If you must use a GUI interface at the console, remove the commands that automatically start the window manager from the .RC startup directories and then create a startup command for the window manager. You can then use the window manager when you need to work on the system, but shut it down when you are done. Do not leave the window manager running for any extended length of time. 11. If the machine must be administered remotely, require that a secure capability such as secure shell is used to make a secure connection. Do not allow telnet or non-anonymous ftp (those requiring a username and password) connections to this machine from any untrusted site. It would also be good to limit these connections only to a minimum number of secure machines and have those machines reside within your Intranet. 12. Run the web server in a chroot-ed part of the directory tree so it cannot access the real system files. 13. Run the anonymous FTP server (if you need it) in a chroot-ed part of the directory tree that is different from the web server's tree. 14. Do all updates from your Intranet. Maintain your web page originals on a server on your Intranet and make all changes and updates here; then "push" these updates to the public server through an SSL connection. If you do this on a hourly basis, you can avoid having a corrupted server exposed for a long period of time. 15. Scan your web server periodically with tools like ISS or nmap to look for vulnerabilities. 16. Have intrusion detection software monitor the connections to the server. Set the detector to alarm on known exploits and suspicious activities and to capture these sessions for review. This information can help you recover from an intrusion and strengthen your defenses. BULLETINS PUBLISHED RELATING TO WEB SERVERS: ========== UNIX Systems CIAC Bulletins: F-11: Unix NCSA httpd Vulnerability http://www.ciac.org/ciac/bulletins/f-11.shtml H-01: Vulnerabilities in bash http://www.ciac.org/ciac/bulletins/h-01.shtml I-024: CGI Security Hole in EWS1.1 Vulnerability http://www.ciac.org/ciac/bulletins/i-024.shtml I-082: HP-UX Netscape Servers Vulnerability http://www.ciac.org/ciac/bulletins/i-082.shtml I-040: SGI Netscape Navigator Vulnerabilities http://www.ciac.org/ciac/bulletins/i-040.shtml Other Bulletins: Domino 4.6 may allow unauthorized writes to remote server drives and server configuration files. http://www.l0pht.com/advisories/domino2.txt Excite 1.1 may set encrypted password files world writable. BUGTRAQ Mail Archives: "Security bugs in Excite for Web Servers 1.1" at http://www.netspace.org/cgi-bin/wa?A2=ind9811e&L=bugtraq&F=&S=&P=519 ColdFusion Application Server and unauthorized access to web server data. http://www.excite.com/computers_and_internet/tech_news/zdnet/ ?article=/news/19990429/1014542.inp ========== Windows Systems CIAC Bulletins: I-024: CGI Security Hole in EWS1.1 Vulnerability http://www.ciac.org/ciac/bulletins/i-024.shtml I-025A: Windows NT based Web Servers File Access Vulnerability http://www.ciac.org/ciac/bulletins/i-025a.shtml Microsoft bulletins can be found under the Microsoft Security Advisor web page at http://www.microsoft.com/security/default.asp The following bulletins appeared in "Current Security Bulletins" and "Security Bulletin Archives": MS99-013: Solution Available for File Viewers Vulnerability. (May 7, 1999) MS99-012: MSHTML Update Available for Internet Explorer. (April 21, 1999) MS99-011: Patch Available for "DHTML Edit" Vulnerability. (April 21, 1999) MS98-019: Patch Available for IIS "GET" Vulnerability. (December 21, 1998) MS98-016: Update available for "Dotless IP Address" Issue in Microsoft Internet Explorer 4. (October 23, 1998) MS98-011: Update Available for "Window.External" JScript Vulnerability in Microsoft Internet Explorer 4.0. (August 17, 1998) MS98-004: Unauthorized ODBC Data Access with Remote Data Services and Inernet Information Systems. (July 15, 1998) Other Bulletins: "ISAPI Extension vulnerability allows to execute code as SYSTEM" at: http://www.ntbugtraq.com/page_archives_wa.asp?A2=ind9903&L= ntbugtraq&F=P&S=&P=2439 Internet Explorer 5.0 cached passwords can be reused by another user. http://www.zdnet.com/zdnn/stories/news/0,4586,1014586,00.html http://www.zdnet.com/anchordesk/story/story_3351.html Internet Explorer (3.01, 3.02, 4.0, 4.01) may allow frame spoofing to trick the user Microsoft Knowledgebase Article ID: Q167614: "Update Available For "Frame Spoof" Security Issue" http://support.microsoft.com/support/kb/articles/q167/6/14.asp ========== Systems running NCSA HTTPD and Apache HTTPD CIAC Bulletins: G-17: Vulnerabilities in Sample HTTPD CGIs http://ciac.llnl.gov/ciac/bulletins/g-17.shtml G-20: Vulnerability in NCSA and Apache httpd Servers http://www.ciac.org/ciac/bulletins/g-20.shtml Other Bulletins: Apache denial-of-service attack -- Apache httpd (1.2.x, 1.3b3) http://www.netspace.org/cgi-bin/wa?A1=ind9712e&L=bugtraq#2 http://www.apache.org/dist/patches/apply_to_1.2.4/ no2slash-loop-fix.patch http://www.apache.org/dist/patches/apply_to_1.3b3/ no2slash-loop-fix.patch "HTTP REQUEST_METHOD flaw" http://www.netspace.org/cgi-bin/wa?A2=ind9901a&L=bugtraq&F= &S=&P=8530 ========== Systems running Netscape Navigator CIAC Bulletins: H-76: Netscape Navigator Security Vulnerability http://www.ciac.org/ciac/bulletins/h-76.shtml I-082: HP-UX Netscape Servers Vulnerability http://www.ciac.org/ciac/bulletins/i-082.shtml I-040: SGI Netscape Navigator Vulnerabilities http://www.ciac.org/ciac/bulletins/i-040.shtml Other Bulletins: "Reading local files with Netscape Communicator 4.5" at http://www.geocities.com/ResearchTriangle/1711/b6.html Netscape Navigator may allow frame spoofing to trick the user Netscape Security Update: "The Frame-Spoofing Vulnerability" http://home.netscape.com/products/security/resources/bugs/ framespoofing.html ========== System running cgi-bin routines CIAC Bulletins: I-013: Count.cgi Buffer Overrun Vulnerability http://www.ciac.org/ciac/bulletins/i-013.shtml I-014: Vulnerability in GlimpseHTTP and WebGlimpse cgi-bin Packages http://www.ciac.org/ciac/bulletins/i-014.shtml Other Bulletins: IRIX webdist.cgi, handler and wrap programs ftp://sgigate.sgi.com/security/19970501-02-PX ftp://info.cert.org/pub/cert_advisories/CA-97.12.webdist "Nlog 1.1b released - security holes fixed" http://www.netspace.org/cgi-bin/wa?A2=ind9812d&L=bugtraq&F=&S= &P=10302 http://owned.comotion.org/~spinux/index.html ========== CIAC also published a document called Securing Internet Information Servers which has a chapter on Securing World Wide Web Servers http://www.ciac.org/ciac/documents/ciac2308.html There are other resources that CIAC recommends for additional guidance. The first is a publication that was developed by SANS and The Intranet Institute after the web server at the U.S. Department of Justice was hacked--"Twelve Mistakes To Avoid In Managing Security-For the Web." The document can be found at: http://www.computerworld.com/home/online9697.nsf/all/971001secure. SANS also publishes a document called "14 Steps to Avoiding Disaster with Your Web Site." Another web site that you should book mark is http://www.w3.org/Security/faq/. This is a web security FAQ (Frequently Asked Questions) that is maintained by The World Wide Web Consortium http://www.w3.org/. They have security sections for each of the major operating systems used today for web servers: http://www.w3.org/Security/faq/wwwsf8.html. IF YOUR WEB SITE HAS BEEN HACKED: CIAC recommends the following as you check your web servers: 1. Apply ALL security-related patches for the web server software as well as for the underlying Operating System. 2. Remove ALL unnecessary files such as phf from the scripts directory /cgi-bin. Remove the "default" document trees that are shipped with Web servers such as IIS and ExAir. 3. Validate ALL user accounts on the web server and ensure that they have strong passwords. 4. Validate ALL services and open ports on the web server to ensure there are no Trojanned services. 5. Look for suspicious files in the /dev, /etc, and /tmp directories. ______________________________________________________________________________ CIAC, the Computer Incident Advisory Capability, is the computer security incident response team for the U.S. Department of Energy (DOE) and the emergency backup response team for the National Institutes of Health (NIH). CIAC is located at the Lawrence Livermore National Laboratory in Livermore, California. CIAC is also a founding member of FIRST, the Forum of Incident Response and Security Teams, a global organization established to foster cooperation and coordination among computer security teams worldwide. CIAC services are available to DOE, DOE contractors, and the NIH. CIAC can be contacted at: Voice: +1 925-422-8193 FAX: +1 925-423-8002 STU-III: +1 925-423-2604 E-mail: ciac@llnl.gov For emergencies and off-hour assistance, DOE, DOE contractor sites, and the NIH may contact CIAC 24-hours a day. During off hours (5PM - 8AM PST), use one of the following methods to contact CIAC: 1. Call the CIAC voice number 925-422-8193 and leave a message, or 2. Call 888-449-8369 to send a Sky Page to the CIAC duty person (PIN number 8550070), or 3. Send e-mail to 4498369@skytel.com, or 4. Call 800-201-9288 for the CIAC Project Leader. Previous CIAC notices, anti-virus software, and other information are available from the CIAC Computer Security Archive. World Wide Web: http://www.ciac.org/ (or http://ciac.llnl.gov) Anonymous FTP: ftp.ciac.org (or ciac.llnl.gov) Modem access: +1 (925) 423-4753 (28.8K baud) +1 (925) 423-3331 (28.8K baud) CIAC has several self-subscribing mailing lists for electronic publications: 1. CIAC-BULLETIN for Advisories, highest priority - time critical information and Bulletins, important computer security information; 2. SPI-ANNOUNCE for official news about Security Profile Inspector (SPI) software updates, new features, distribution and availability; 3. SPI-NOTES, for discussion of problems and solutions regarding the use of SPI products. Our mailing lists are managed by a public domain software package called Majordomo, which ignores E-mail header subject lines. To subscribe (add yourself) to one of our mailing lists, send the following request as the E-mail message body, substituting ciac-bulletin, spi-announce OR spi-notes for list-name: E-mail to ciac-listproc@llnl.gov or majordomo@rumpole.llnl.gov: subscribe list-name e.g., subscribe ciac-bulletin You will receive an acknowledgment email immediately with a confirmation that you will need to mail back to the addresses above, as per the instructions in the email. This is a partial protection to make sure you are really the one who asked to be signed up for the list in question. If you include the word 'help' in the body of an email to the above address, it will also send back an information file on how to subscribe/unsubscribe, get past issues of CIAC bulletins via email, etc. PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing communities receive CIAC bulletins. If you are not part of these communities, please contact your agency's response team to report incidents. Your agency's team will coordinate with CIAC. The Forum of Incident Response and Security Teams (FIRST) is a world-wide organization. A list of FIRST member organizations and their constituencies can be obtained via WWW at http://www.first.org/. This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. LAST 10 CIAC BULLETINS ISSUED (Previous bulletins available from CIAC) J-032: Windows Backdoors Update II: J-033: SGI X server font path vulnerability J-034: Cisco 7xx TCP and HTTP Vulnerabilities J-035: Linux Blind TCP Spoofing J-036: LDAP Buffer overflow against Microsoft Directory Services J-037: W97M.Melissa Word Macro Virus J-038: HP-UX Vulnerabilities (hpterm, ftp) J-039: HP-UX Vulnerabilities (MC/ServiceGuard & MC/LockManager, DES J-040: HP-UX Security Vulnerability in sendmail J-041: Cisco IOS(R) Software Input Access List Leakage with NAT -----BEGIN PGP SIGNATURE----- Version: 4.0 Business Edition iQCVAwUBN0CwKbnzJzdsy3QZAQHXtQP/XjIp+n8AXt3NeZM0TJ4eQ/aYzcow0v8e 3yrlDn4QmBtamNdDF0ghXpUoUyq6y/ZeWD8Dle4lY8Do54BhtUI9lvfCh+3XzhVm wuQ9Tw7rS11yN/NoP+wi6YH3vsLqbWyeC3a/cR8IdAmU2NHNBvADh9mYvsaVKQi8 OOvrn56na4Y= =1ind -----END PGP SIGNATURE-----