Type packetstorm
Reporter Packet Storm
Modified 1999-08-17T00:00:00


                                            `Date: Tue, 18 May 1999 09:09:34 -0700 (PDT)  
From: CIAC Mail User <>  
Subject: CIAC Bulletin J-042: Web Security  
[ For Public Release ]  
The U.S. Department of Energy  
Computer Incident Advisory Capability  
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\___ __|__ / \ \___  
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  
VULNERABILITY Public web sites are hacked on an almost daily basis; the  
ASSESSMENT: threat that your site could be compromised is real.  
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  
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  
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.  
UNIX Systems  
CIAC Bulletins:  
F-11: Unix NCSA httpd Vulnerability  
H-01: Vulnerabilities in bash  
I-024: CGI Security Hole in EWS1.1 Vulnerability  
I-082: HP-UX Netscape Servers Vulnerability  
I-040: SGI Netscape Navigator Vulnerabilities  
Other Bulletins:  
Domino 4.6 may allow unauthorized writes to remote server drives and  
server configuration files.  
Excite 1.1 may set encrypted password files world writable.  
BUGTRAQ Mail Archives: "Security bugs in Excite for Web Servers 1.1"  
ColdFusion Application Server and unauthorized access to web server data.  
Windows Systems  
CIAC Bulletins:  
I-024: CGI Security Hole in EWS1.1 Vulnerability  
I-025A: Windows NT based Web Servers File Access Vulnerability  
Microsoft bulletins can be found under the Microsoft Security  
Advisor web page at  
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:  
Internet Explorer 5.0 cached passwords can be reused by another user.,4586,1014586,00.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"  
Systems running NCSA HTTPD and Apache HTTPD  
CIAC Bulletins:  
G-17: Vulnerabilities in Sample HTTPD CGIs  
G-20: Vulnerability in NCSA and Apache httpd Servers  
Other Bulletins:  
Apache denial-of-service attack -- Apache httpd (1.2.x, 1.3b3)  
Systems running Netscape Navigator  
CIAC Bulletins:  
H-76: Netscape Navigator Security Vulnerability  
I-082: HP-UX Netscape Servers Vulnerability  
I-040: SGI Netscape Navigator Vulnerabilities  
Other Bulletins:  
"Reading local files with Netscape Communicator 4.5" at  
Netscape Navigator may allow frame spoofing to trick the user  
Netscape Security Update: "The Frame-Spoofing Vulnerability"  
System running cgi-bin routines  
CIAC Bulletins:  
I-013: Count.cgi Buffer Overrun Vulnerability  
I-014: Vulnerability in GlimpseHTTP and WebGlimpse cgi-bin Packages  
Other Bulletins:  
IRIX webdist.cgi, handler and wrap programs  
"Nlog 1.1b released - security holes fixed"  
CIAC also published a document called Securing Internet Information  
Servers which has a chapter on Securing World Wide Web Servers  
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:  
SANS also publishes a document called "14 Steps to Avoiding Disaster  
with Your Web Site."  
Another web site that you should book mark is  
This is a web security FAQ (Frequently Asked Questions) that is maintained  
by The World Wide Web Consortium They have security  
sections for each of the major operating systems used today for web servers:  
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  
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, 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:  
Anonymous FTP:  
Modem access: +1 (925) 423-4753 (28.8K baud)  
+1 (925) 423-3331 (28.8K baud)  
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PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing  
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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  
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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  
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