Tomcat may reveal script source code by URL trickery 2
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Sverre H. Huseby security advisory #4, 2001-04-03



Systems affected
----------------

Tomcat 4.0-b2, which includes fixes for a similar bug.  Other versions
before 4.0-b3 may be vulnerable too.

The Tomcat team was notified on 2001-04-01, and they provided a fix on
2001-04-03.  Everybody should upgrade to at least Tomcat 4.0 beta 3.


Description
-----------

Tomcat (http://jakarta.apache.org/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.


Details
-------

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

  http://someplace.com:8080/index.js%2570

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).


Impact
------

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, shh@thathost.com