maldet(1)

LINUX-MALWARE-DETECT(19)

User Commands

LINUX-MALWARE-DETECT(19)

NAME

maldet - Linux Malware Detect

SYNOPSIS

DESCRIPTION

Linux Malware Detect is a malware scanner for Linux released under the GNU GPLv2 license, that is designed around the threats faced in shared hosted environments. It uses threat data from network edge intrusion detection systems to extract malware that is actively being used in attacks and generates signatures for detection. In addition, threat data is also derived from user submissions with the LMD checkout feature and from malware community resources. The signatures that LMD uses are MD5 file hashes and HEX pattern matches, they are also easily exported to any number of detection tools such as ClamAV.

The driving force behind LMD is that there is currently limited availability of open source/restriction free tools for Linux systems that focus on malware detection and more important that get it right. Many of the AV products that perform malware detection on Linux have a very poor track record of detecting threats, especially those targeted at shared hosted environments.

The threat landscape in shared hosted environments is unique from that of the standard AV products detection suite in that they are detecting primarily OS level trojans, rootkits and traditional file-infecting viruses but missing the ever increasing variety of malware on the user account level which serves as an attack platform.

FEATURES

MD5 file hash detection for quick threat identification
HEX based pattern matching for identifying threat variants
statistical analysis component for detection of obfuscated threats (e.g: base64)
integrated detection of ClamAV to use as scanner engine for improved performance
integrated signature update feature with -u|--update
integrated version update feature with -d|--update-ver
scan-recent option to scan only files that have been added/changed in X days
scan-all option for full path based scanning
checkout option to upload suspected malware to rfxn.com for review / hashing
full reporting system to view current and previous scan results
quarantine queue that stores threats in a safe fashion with no permissions
quarantine batching option to quarantine the results of a current or past scans
quarantine restore option to restore files to original path, owner and perms
quarantine suspend account option to Cpanel suspend or shell revoke users
cleaner rules to attempt removal of malware injected strings
cleaner batching option to attempt cleaning of previous scan reports
cleaner rules to remove base64 and gzinflate(base64 injected malware
daily cron based scanning of all changes in last 24h in user homedirs
daily cron script compatible with stock RH style systems, Cpanel & Ensim
kernel based inotify real time file scanning of created/modified/moved files
kernel inotify monitor that can take path data from STDIN or FILE
kernel inotify monitor convenience feature to monitor system users
kernel inotify monitor can be restricted to a configurable user html root
kernel inotify monitor with dynamic sysctl limits for optimal performance
kernel inotify alerting through daily and/or optional weekly reports
e-mail alert reporting after every scan execution (manual & daily)
path, extension and signature based ignore options
background scanner option for unattended scan operations
verbose logging & output of all actions

THREAT SOURCE DATA

The defining difference with LMD is that it doesn't just detect malware based on signatures/hashes that someone else generated but rather it is an encompassing project that actively tracks in the wild threats and generates signatures based on those real world threats that are currently circulating.

There are four main sources for malware data that is used to generate LMD signatures:

Network Edge IPS: The network I manage hosts over 35,000 web sites and as such receives a large amount of daily abuse, all of which is logged by our network edge IPS. The IPS events are processed to extract malware url's, decode POST payload and base64/gzip encoded abuse data and ultimately that malware is retrieved, reviewed, classified and then signatures generated as appropriate. The vast majority of LMD signatures have been derived from IPS extracted data.
Community Data: Data is aggregated from multiple community malware websites such as clean-mx and malwaredomainlist then processed to retrieve new malware, review, classify and then generate signatures.
ClamAV: The HEX & MD5 detection signatures from ClamAV are monitored for relevant updates that apply to the target user group of LMD and added to the project as appropriate. To date there has been roughly 400 signatures ported from ClamAV while the LMD project has contributed back to ClamAV by submitting over 1,100 signatures and continues to do so on an ongoing basis.
User Submission: LMD has a checkout feature that allows users to submit suspected malware for review, this has grown into a very popular feature and generates on average about 30-50 submissions per week.

SIGNATURE UPDATES

The LMD signatures are updated typically once per day or more frequently depending on incoming threat data from the LMD checkout feature, IPS malware extraction and other sources. The updating of signatures in LMD installations is performed daily through the default cron.daily script with the --update option, which can be run manually at any time.

An RSS feed is available for tracking malware threat updates:: RSS Recent Signatures: http://www.rfxn.com/api/lmd

CLI USAGE

The command line options are as follows:

-b, --background

: Execute operations in the background, ideal for large scans e.g: maldet -b -r /home/?/public_html 7

-u, --update-sigs

: Update malware detection signatures from rfxn.com

-f, --file-list

: Scan files or paths defined in line spaced file e.g: maldet -f /root/scan_file_list

-r, --scan-recent PATH DAYS

: Scan files created/modified in the last X days (default: 7d, wildcard: ?) e.g: maldet -r /home/?/public_html 2

-a, --scan-all PATH

: Scan all files in path (default: /home, wildcard: ?) e.g: maldet -a /home/?/public_html

-i, --include-regex REGEX

: Include paths/files from file list based on supplied posix-egrep regular expression. e.g: To include only paths named wp-content and files ending in .php: --include-regex ".*/wp-content/.*|.*.php$"

-x, --exclude-regex REGEX

: Exclude paths/files from file list based on supplied posix-egrep regular expression. e.g: To exclude paths containing 'wp-content/w3tc/' and core files: --exclude-regex ".*wp-content/w3tc/.*|.*core.[0-9]+$"

-m, --monitor USERS|PATHS|FILE|RELOAD

: Run maldet with inotify kernel level file create/modify monitoring If USERS is specified, monitor user homedirs for UID's > 500 If FILE is specified, paths will be extracted from file, line spaced If PATHS are specified, must be comma spaced list, NO WILDCARDS! e.g: maldet --monitor users e.g: maldet --monitor /usr/local/maldetect/monitor_paths e.g: maldet --monitor /home/mike,/home/ashton

-k, --kill-monitor

: Terminate inotify monitoring service

-c, --checkout FILE

: Upload suspected malware to rfxn.com for review & hashing into signatures

-l, --log

: View maldet log file events

-e, --report SCANID email

: View scan report of most recent scan or of a specific SCANID and optionally e-mail the report to a supplied e-mail address e.g: maldet --report e.g: maldet --report list e.g: maldet --report 050910-1534.21135 e.g: maldet --report SCANID user@domain.com

-s, --restore FILE|SCANID

: Restore file from quarantine queue to orginal path or restore all items from a specific SCANID e.g: maldet --restore /usr/local/maldetect/quarantine/config.php.23754 e.g: maldet --restore 050910-1534.21135

-q, --quarantine SCANID

: Quarantine all malware from report SCANID e.g: maldet --quarantine 050910-1534.21135

-n, --clean SCANID

: Try to clean & restore malware hits from report SCANID e.g: maldet --clean 050910-1534.21135

-U, --user USER

: Set execution under specified user, ideal for restoring from user quarantine or to view user reports. e.g: maldet --user nobody --report e.g: maldet --user nobody --restore 050910-1534.21135

-co, --config-option VAR1=VALUE,VAR2=VALUE,VAR3=VALUE

: Set or redefine the value of maldetect.conf config options e.g: maldet --config-option email_addr=you@domain.com,quarantine_hits=1

-p, --purge

: Clear logs, quarantine queue, session and temporary data.

LICENSE

This program may be freely redistributed under the terms of the GNU GPL v2

AUTHORS

September 2016

Linux Malware Detect v1.6.4