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Bugtraq archives for 2nd quarter (Apr-Jun) 1999: Netscape Communicator bookmarks <TITLE> security vulnerability

Netscape Communicator bookmarks <TITLE> security vulnerability

Georgi Guninski (joroNAT.BG)
Sun, 16 May 1999 17:17:34 +0300 

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There is a security bug in Netscape Communicator 4.51 Win95, 4.07 Linux
(guess all 4.x versions are affected) in the way they handle special
bookmarks
with JavaScript code in the title.

If you enclose a JavaScript code with <SCRIPT> tags in the <TITLE>
tag and bookmark that page, the JavaScript code is written in the local
bookmarks file.
Then when the bookmarks file is open, the JavaScript code is executed in
the security
context of a local file - the bookmarks file.
The bookmarks file may be open by a script, probably a server redirect
or by the user.
The bookmarks file name must be known, but it is easily guessed for most
dialup
users.

Vulnerabilities: reading user's bookmarks, browsing local directories,
reading local files (works fine on Linux, probably possible on Windows).

Workaround: Disable JavaScript or do not bookmark untrusted pages.

Demonstration is available at: http://www.nat.bg/~joro/book2.html
See attached file for the source.

Georgi Guninski
 http://www.nat.bg/~joro
 http://www.whitehats.com/guninski
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 name="book2.html"
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 filename="book2.html"
<SCRIPT> alert('Bookmarks got control'); s='Here are some bookmarks: \n'; for(i=1;i<7;i++) s += document.links[i]+'\n'; alert(s); dirToRead='wysiwyg://2/file://c:/'; a=window.open(dirToRead); s='Here are some files in C:\\ :\n'; for(i=1;i<7;i++) s += a.document.links[i]+'\n'; a.close(); alert(s); </SCRIPT> There is a security bug in Netscape Communicator 4.51 Win95, 4.07 Linux (guess all 4.x versions are affected) in the way they handle special bookmarks with Javascript code in the title.
If you enclose a JavaScript code with <SCRIPT> tags in the <TITLE> tag and bookmark that page, the JavaScript code is written in the local bookmarks file. Then when the bookmarks file is open, the JavaScript code is executed in the security context of a local file. The bookmarks file may be open by a script, probably a server redirect or by the user. The bookmarks file name must be known - easily guessed for most dialup users.

Vulnerability: reading user's bookmarks, browsing local directories, reading local files (works fine on Linux, probably possible on Windows).
Workaround: Disable JavaScript or do not bookmark untrusted pages.


To test it:
1) Bookmark this page.
2) Close all NC windows and restart NC.
3) Open bookmarks file (change the filename in the field below if needed and click "Open bookmarks", or use File| Open Page... )
Enter the file name of your bookmarks file:
Open bookmarks
Go to Georgi Guninski's home page 
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