Allaire JRUN 2.3 Remote command execution

                        Foundstone, Inc.
                    http://www.foundstone.com
                  "Securing the Dot Com World"

                       Security Advisory

                       Allaire JRUN 2.3

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FS Advisory ID: FS-102300-14-JRUN

Release Date: October 23, 2000

Product: Allaire JRUN 2.3

Vendor: Allaire Inc. (http://www.allaire.com)

Vendor Advisory: http://www.allaire.com/security/

Type: Remote command execution

Severity: High

Author: Shreeraj Shah ([email protected])
Saumil Shah ([email protected])
Stuart McClure ([email protected])
Foundstone, Inc. (http://www.foundstone.com)

Operating Systems: All operating systems supported by JRUN

Vulnerable versions: JRUN Server v2.3

Foundstone Advisory:
http://www.foundstone.com/cgi-bin/display.cgi?Section_ID=13

Description

    It is possible to compile and execute any arbitrary file
    within the web document root directory of the JRUN's web
    server as if it were a JSP file, even if the file type is not
    .jsp.

    If applications running on the JRUN 2.3 server write to files
    within the web document root directory, it is possible to
    insert executable code in the form of JSP tags and have the
    code compiled and executed using JRUN's handlers. This can
    potentially cause an attacker to gain administrative control
    of the underlying operating systems.

    The theory behind such vulnerabilities is described in CERT
    Advisory CA-2000-02 which can be found at:
    http://www.cert.org/advisories/CA-2000-02.html

    This vulnerability is similar to the remote execution
    vulnerability for Sun's Java Web Server and BEA's WebLogic
    application server reported previously by Foundstone.
    (FS-071000-5-JWS and FS-073100-10-BEA)

Details

    From the rules.properties and servlets.properties file, it is
    seen that the URL prefix /servlet/ can be used as an invoker
    for any servlet. Also, the JRUN servlet engine handles all jsp
    requests by invoking the com.livesoftware.jrun.plugins.JSP
    servlet.

    It is possible to invoke these servlets manually, even if they
    are not registered in the JRUN configuration, using the
    complete name in the URL prefixed by /servlet/, and point it
    to any arbitrary file on the web server. This file will be
    then compiled and executed as if it were a JSP file. If JSP
    code can be injected into any file on the web server via an
    application (e.g. a guestbook application), it is possible to
    execute arbitrary commands on the server.

Proof of concept

    Assume that there is an application on the JRUN server that
    writes user entered data to a file called "temp.txt".

    Given below is JSP code that will print "Hello World":

    <% out.println("Hello World"); %>

    If this code is somehow inserted in the file "temp.txt" via an
    application, then the following two URLs can be used to invoke
    forced compilation and execution of "temp.txt":

http://jrun:8000/servlet/com.livesoftware.jrun.plugins.jsp.JSP/../../path/to
/temp.txt
http://jrun:8000/servlet/jsp/../../path/to/temp.txt

    Note: It is assumed that JRun runs on host "jrun", port 8000.

Solution

    Follow the recommendations given in Allaire Security Bulletin
    ASB00-29, available at: http://www.allaire.com/security/

Credits

    We would also like to thank Allaire for their prompt reaction
    to this problem and their co-operation in heightening
    security awareness in the security community.

Disclaimer

    The information contained in this advisory is the copyright
    (C) 2000 of Foundstone, Inc. and believed to be accurate at
    the time of printing, but no representation or warranty is
    given, express or implied, as to its accuracy or completeness.
    Neither the author nor the publisher accepts any liability
    whatsoever for any direct, indirect or conquential loss or
    damage arising in any way from any use of, or reliance placed
    on, this information for any purpose. This advisory may be
    redistributed provided that no fee is assigned and that the
    advisory is not modified in any way.