External malware block list

The external malware block list allows users to add their own malware signatures in the form of MD5, SHA1, and SHA256 hashes. The FortiGate's antivirus database retrieves an external malware hash list from a remote server and polls the hash list every n minutes for updates. Enabling the AV engine scan is not required to use this feature.

The external malware block list can be used in both proxy-based and flow-based policy inspections, but it is not supported in AV quick scan mode.

Note that using different types of hashes simultaneously may slow down the performance of malware scanning. It is recommended to use one type of hash.

To create the external block list:

1. Create the malware hash list.

   The malware hash list follows a strict format in order for its contents to be valid. Malware hash signature entries must be separated into each line. A valid signature needs to follow this format:

   # MD5 Entry with hash description
   aa67243f746e5d76f68ec809355ec234  md5_sample1
   
   # SHA1 Entry with hash description
   a57983cb39e25ab80d7d3dc05695dd0ee0e49766  sha1_sample2
   
   # SHA256 Entry with hash description
   ae9bc0b4c5639d977d720e4271da06b50f7c60d1e2070e9c75cc59ab30e49379  sha256_sample1
   
   # Entry without hash description
   0289b0d967cb7b1fb1451339c7b9818a621903090e0020366ab415c549212521
   
   # Invalid entries
   7688499dc71b932feb126347289c0b8a_md5_sample2
   7614e98badca10b5e2d08f8664c519b7a906fbd5180ea5d04a82fce9796a4b87sha256_sample3

2. Configure the external malware block list source:
   1. Go to Security Fabric > External Connectors and click Create New.
   2. Click Malware Hash.
   3. Configure the settings as needed. The URI must point to the malware hash list on the remote server.
   4. Click OK.
3. To view entries inside the malware block list on the External Connectors page, hover over the malware hash card and click View Entries.

To configure antivirus to use an external block list in the GUI:

1. Go to Security Profiles > AntiVirus and edit the antivirus profile.
2. In the Virus Outbreak Prevention section, enable Use external malware block list and click Specify.
3. Click the + in the field and select a threat feed.
4. Optionally, enable Quarantine.

   

5. Configure the other settings as needed.
6. Click OK.

To configure antivirus to use an external block list in the CLI:

config antivirus profile
    edit "Demo"
        set feature-set proxy
        set mobile-malware-db enable
        config http
            set av-scan disable
            set outbreak-prevention block
            set external-blocklist block
            set quarantine enable
            set emulator enable
            set content-disarm disable
        end
        config ftp
            set av-scan disable
            set outbreak-prevention block
            set external-blocklist block
            set quarantine enable
            set emulator enable
        end
        config imap
            set av-scan monitor
            set outbreak-prevention block
            set external-blocklist block
            set quarantine enable
            set emulator enable
            set executables default
            set content-disarm disable
        end
        config pop3
            set av-scan monitor
            set outbreak-prevention block
            set external-blocklist block
            set quarantine enable
            set emulator enable
            set executables default
            set content-disarm disable
        end
        config smtp
            set av-scan monitor
            set outbreak-prevention block
            set external-blocklist block
            set quarantine enable
            set emulator enable
            set executables default
            set content-disarm disable
        end
        config mapi
            set av-scan monitor
            set outbreak-prevention block
            set external-blocklist block
            set quarantine enable
            set emulator enable
            set executables default
        end
        config nntp
            set av-scan disable
            set outbreak-prevention disable
            set external-blocklist disable
            set quarantine disable
            set emulator enable
        end
        config cifs
            set av-scan monitor
            set outbreak-prevention block
            set external-blocklist block
            set quarantine enable
            set emulator enable
        end
        config ssh
            set av-scan disable
            set outbreak-prevention disable
            set external-blocklist disable
            set quarantine disable
            set emulator enable
        end
        set outbreak-prevention-archive-scan enable
set external-blocklist-enable-all disable
        set external-blocklist "malhash1"
        set av-virus-log enable
        set av-block-log enable
        set extended-log disable
        set scan-mode default
    next
end

The quarantine setting is configured in each protocol (set quarantine). The malware threat feed is also specified (set external-blocklist-enable-all disable) to the threat connector, malhash1 (set external-blocklist "malhash1").

To verify the scanunit daemon updated itself with the external hashes:

# diagnose sys scanunit malware-list list
md5 'aa67243f746e5d76f68ec809355ec234' profile 'malhash1' description 'md5_sample1'
sha1 'a57983cb39e25ab80d7d3dc05695dd0ee0e49766' profile 'malhash1' description 'sha1_sample2'
sha256 '0289b0d967cb7b1fb1451339c7b9818a621903090e0020366ab415c549212521' profile 'malhash1' description ''
sha256 'ae9bc0b4c5639d977d720e4271da06b50f7c60d1e2070e9c75cc59ab30e49379' profile 'malhash1' description 'sha256_sample1'