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| Novell's Netware 5.1 ships with a Web Server that is installed by default and contains various sample web pages. There is a "viewcode" application that runs through a Netware Loadable Module (NLM), which allows the source code of a default web page to be viewed. However, the NLM has the sample page name passed to it through a URL containing the path to the file. It is possible to alter the URL to permit the contents of any file on the system to be viewed even those situated outside the web root. With this method, it is possible to view important configuration files including the autoexec.ncf file that contains the remote console password. |
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Credit:
The information has been provided by IRM Security Advisories.
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Vulnerable systems:
Netware Web Server version 5.1
Netware is an Operating System developed by Novell and used by many organizations for user file and print sharing. Version 5.1 of the Netware Operating system comes with a web server that is installed by default. Included on the web server are a wide variety of sample pages that demonstrate the flexibility and features of the product. However, one sample page uses a Netware Loadable Module (NLM) called sewse.nlm to call a script called viewcode.jse. The viewcode.jse file displays the source code of sample files called httplist.htm and httplist.jse. These file names are passed as parameters to the NLM through a URL such as (URL may wrap):
http://10.0.25.5/lcgi/sewse.nlm?
sys:/novonyx/suitespot/docs/sewse/viewcode.jse+httplist/httplist.htm+httplist/httplist.jse
The application checks the files being requested by requiring that the httplist directory is specified in the path to the files to be viewed. However, it is possible to traverse directories using /../ after httplist. The sewse.nlm module runs with sufficient permissions whereby it possible to traverse to any files in the file system and view its content.
There are many files that may be of interest to an attacker and these include:
SYS:\ETC\NETINFO.CFG - Can contain a copy of the rconsole password
SYS:\SYSTEM\AUTOEXEC.NCF - Contains the rconsole password
SYS:\ETC\FTPAUDIT.LOG - Contains valid usernames for password guessing attempts
An attacker could use the information gained to launch further attacks or to gain console access using the rconsole password. An example of the URL used to view the autoexec.ncf is (URL may wrap):
http://10.0.25.5/lcgi/sewse.nlm?
sys:/novonyx/suitespot/docs/sewse/viewcode.jse+httplist+httplist/../../../../../system/autoexec.ncf
There are Novell best practices that include encrypting the rconsole password in the autoexec.ncf file. However, there are tools available that can be used to break this encryption. Another Novell recommendation is to use a Console Screensaver that requires the admin password to be entered after an rconsole connection has been made. This issue is similar to the problem discovered with the convert.bas script that shipped with Netware Web Server version 2.0.
Vendor & patch information:
The vendor of this product, Novell, was contacted via email using the address listed as their 'community relations' on 20 November 2001. When no reply was received to this email after nine days, another email was sent on 29 November 2001 to the same address, and copied to 'secure@novell.com'. No reply from either address had been received as of December 11 2001.
Workarounds:
A workaround involves removing all sample web pages and sample NLMs.
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