Re: Norton Internet Security Blocked Sites XSS
From: Sym Security (symsecurity_at_SYMANTEC.COM)
Date: Tue, 28 Oct 2003 13:25:24 -0600 To: NTBUGTRAQ@LISTSERV.NTBUGTRAQ.COM
On 10/27/2003 01:27 PM, DigitalPranksters posted the following to
DigitalPranksters Security Advisory
Norton Internet Security Blocked Sites XSS
Product: Norton Internet Security 2003 v18.104.22.168 (Maybe others we only
tested this version)
Product URL: http://www.symantec.com/sabu/nis/nis_pe/index.html
Found By: KrazySnake - email@example.com
When Norton Internet Security 2003 blocks a web site, it returns a web
page to the browser stating that the site has been blocked. This error
message contains the URL which was requested. Norton Internet Security
2003 appears to do no validation or encoding of the URL before returning
it in the error message. This allows an attacker to supply a URL that
contains script. This script will run in the context of the blocked site.
We have marked this as a low risk because we believe in most situations,
there will be little information of interest since the site is normally
blocked (browser cookies from the blocked site probably do not exist,
etc). However this does allow sites that are blocked to run script on the
victim's machine when it shouldn't be allowed.
Symantec Security Advisory
27 October 2003
Symantec Network Internet Security (NIS) Blocked Site Return Messages Not
A security group, The Digital Pranksters, reported an issue they
discovered in Symantec's Norton Internet Security product.
The URL in the return message from a site on the blocked list in the
Norton Parental Control feature can allow an unauthorized
script to run the client system.
Symantec's Norton Internet Security 2003
Symantec's Norton Internet Security 2004
Symantec's Norton Internet Security blocks inappropriate web content to
help parents keep their children safe from
inappropriate material while online. The Norton Parental Control blocks
access to newsgroups and Web sites that may not be
suitable for children. When a link is accessed or followed to one of the
sites on the blocked list, Norton Internet Security
returns a message stating that the site is restricted and has been
blocked. The returned message included the URL of the
restricted site and is presented in a separate browser window Norton
Internet Security opens on the client system. Digital
Pranksters reported that they were able to supply a URL from a blocked
site that contained additional unauthorized script
embedded in the URL. This script displayed in the blocked access message
window on the client system.
Symantec has verified this issue. There is a bug in the way Norton
Internet Security is validating the content it returns in
the informational page. This is being fixed and will be forthcoming in a
future LiveUpdate to Norton Internet Security
The risk presented by this bug is very low to non-existent. Any
unauthorized script returned in the blocked site URL runs in
the context of the informational window that Norton Internet Security
opens on the client system. This is a very restricted
environment providing no access to the client system outside of the
display window or any unauthorized information from the
client system to be sent out. While it presents little risk to the client
system, it is unwarranted action that is being
Symantec takes any potential security issues with Symantec products very
seriously. While the issue described by the Digital
Pranksters applies only to the subset of Web sites contained in the Norton
Internet Security Block Site list, there are many
other malicious Web sites on the Internet and many ways of enticing a
careless surfer to visit such a site. Symantec recommends
the following best practices as part of a normal security posture:
* Keep vendor-supplied security patches and updates for all application
software and operating systems current.
* Run current Anti-Virus/Firewall applications and keep the definitions
updated. Systems should be scanned on a regular basis.
* Be wary of attachments delivered via email. Especially ones with vbs,
.bat, .exe, .pif and .scr file extensions that are
commonly used to spread viruses, worms, and trojans.
* Even if the sender is known, users should be wary of attachments or
unknown files if the sender does not thoroughly explain
the content in the body of the email. The source of the original
attachment is often unknown.
* If in doubt, users should contact the sender before opening the
attachment or downloading the file to see if, in fact, they
did intend to send it. If there is still doubt, users should delete the
document in question without opening it.
* If you intend to download an attachment, download to a separate folder
and scan prior to opening.
* Practice safe surfing.
Symantec takes the security and proper functionality of our products very
seriously. Symantec appreciates the coordination of
Digital Pranksters security team in identifying and providing details of
this area of concern as well as working closely with
Symantec to properly address the issue. Anyone with information on
security issues or concerns with Symantec products should
Copyright (c) 2003 by Symantec Corp.
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it is not edited in any way unless authorized by
Symantec Security Response. Reprinting the whole or parts of this alert in
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The information in the advisory is believed to be accurate at the time of
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Symantec Security Response
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