It is said that “given enough eyeballs, all bugs are shallow”, which is true, but the tricky part is finding enough eyeballs, especially useful ones and not the ones in that jar in Blade Runner.

Recently, an end user reported a rather severe security issue with OpenNMS.

The process that serves up the “Categories” section on the front page of the web interface is called RTC (for Real Time Console). The database queries that create the availability numbers on that page can be expensive in terms of resources, so the RTC daemon was created to periodically query the database and then cache the results so that lots of users wouldn’t create an undo load on the system.

We use a tool called Castor to process XML data within OpenNMS. Due to a bug in Castor, if Castor discovers an error when processing an XML file, it can throw an exception that includes the contents of the file.

This is very useful when the files relate to OpenNMS and you are trying to debug them, but you don’t exactly want the contents of /etc/shadow or /etc/passwd displayed indiscriminately. That’s exactly what this exploit allows.

Since the default username and password for the RTC user is “rtc” and exists on every system, a malicious person could use that information to obtain the contents of any file on the system. Note that as far as the OpenNMS application is concerned, the RTC user has very limited permissions, but this is caused by an issue with Castor and it has just
enough permissions to trigger it.

This has been reported as our first ever CVE: CVE-2015-0975

The best fix is to upgrade to OpenNMS 14.0.3. If, however, you are unable to upgrade soon, you can edit the Spring security file to limit requests from RTC to just the localhost, which should mitigate most of the issue. Full instructions and files can be found on the wiki.

To summarize, all versions of OpenNMS prior to 14.0.3 contain a bug where *anyone* with access to the webUI (port 8980 on the OpenNMS server) can retrieve any file that is on the system. While this isn’t the end of the world, it definitely could be considered bad and should be addressed.