R-fx Networks

Better Late Than Never: Linux Malware Detect 1.3

by on May.12, 2010, under Development, My Blog

Today I have released Linux Malware Detect (LMD) 1.3, the first public stable release of my malware detection tool. The documentation is a little thin but the details are on the project page and the README file should fill you in on anything you need to know, otherwise you can post a comment on the bottom of the project page and I will assist where possible. Input on feature ideas, bugs and malware data is always welcome, see the –help options on LMD for the checkout feature to upload malware data to rfxn.com.

In October I detailed the concepts behind the then to-be-released LMD in a post, though allot has changed since then in how LMD operates, the jist of the post is still on point.

To those (unfortunate?) enough to ride in on the closed testing, it certainly was a long road and I thank everyone that over time submitted new malware data, bug reports and feature ideas. To say this is the most banged-in release of one of my projects would be understated and I hope it shows in the end product.

So, What has changed since the first incarnations of LMD? Well first is that I ditched the whole “chunked hash” concept for a simpler HEX based pattern matching feature to find malware variants which has proved far more accurate and easier to manage. Though I can see some scaling issues with the current implementation of the HEX scanner as the signature set grows, this is something I do expect to resolve in a future release. The basic MD5 hashed scanning is still the stage-1 scanning component and then the HEX scanner picks up as a stage-2 scanner if no MD5 hit was found.

The kernel based inotify real-time file creation/modification monitoring has been reworked and now more gracefully handles users of any type in addition to monitoring the /dev/shm, /var/tmp and /tmp paths on execution of the monitoring component. Also changed is that the scanner will now batch through new/changed files every 30 seconds for the sake of efficiency but this can easily be modified in the internals.conf down to as low as a 1 second iteration on the scanning of new/changed files.

The quarantine queue now stores files original path, owner and mode to facilitate a –restore feature that allows any file to be restored to its original path with owner and file modes restored as well. This can be used to recover false-positive hits or to restore files after you have cleaned malware from within its contents (default quarantining of malware is now also disabled, see conf.maldet).

The final notable change is that there is now a quarantine suspend account feature, the owning user account (UID>=500) can optionally be Cpanel suspended or have its shell set to /bin/false on non-cpanel systems (configurable in conf.maldet). When Cpanel users are suspended, they will have a comment attached to it with the ‘maldet –report SCANID’ value so you can easily call up the report that suspended the user.

There has been many more changes to LMD but I certainly can not list them all, give it a spin and let me know how it goes, happy malware hunting!

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