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From Jon Stevens <>
Subject FW: [ Tomcat may reveal script source code by URL trickery 2]
Date Mon, 02 Apr 2001 19:24:08 GMT

From: "Sverre H. Huseby" <>
Date: Mon, 2 Apr 2001 21:03:30 +0200
Subject: [ Tomcat may reveal script source code by URL
trickery 2]


I sent the following to a few days ago, as you
requested.  Now I wonder if it reached the correct people.  I see that
you cite "lovehacker" on the Tomcat developer list, even if his
advisory appeared on Bugtraq a day after I sent mine to you.  At least
it showed up a day after in my mailbox.  Comments?


----- Forwarded message from "Sverre H. Huseby" <> -----

From: "Sverre H. Huseby" <>
Subject: Tomcat may reveal script source code by URL trickery 2
Date: Sun, 1 Apr 2001 11:55:00 +0200
User-Agent: Mutt/1.2.5i

NOTE!  This is not the same advisory that I sent you some days ago.
Your fix for that advisory introduced a new bug, which is described

I'm sending you this before contacting Bugtraq this time.  Please tell
me when you have a fix ready.



Tomcat may reveal script source code by URL trickery 2

Sverre H. Huseby security advisory #4, 2001-04-01

Systems affected

Tomcat 4.0-b2, which includes fixes for a similar bug.  Other versions
may be vulnerable too.  The problem is only present when using
Tomcat's built in web server, not when using Tomcat with Apache Web


Tomcat (, the Reference
Implementation for the Java Servlet 2.2 and JavaServer Pages 1.1
Technologies, may be tricked into revealing the source code of JSP
scripts by using simple URL encoding.


It seems that the built in web server in affected versions of Tomcat
does URL decoding twice.  URLs like the following

where %25 is an URL encoded '%', and 70 is the hexadecimal value for
'p', returns the source code of index.jsp rather than running the
script on the server side.

To speculate (read: guess): The JSP handler is skipped as this URL
does not end in ".jsp" (after URL decoding the first time), but the
static file handler is nevertheless able to map the URL into a correct
file name (doing URL decoding a second time).


This design error makes it possible to fetch the source code of JSP
scripts.  Such source code may contain database passwords and file
names, and may reveal design errors or programming bugs that make it
possible to further exploit the server or service.

Reported by Sverre H. Huseby,


----- End forwarded message -----


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