File filter

File Filter allows the Web Filter profile to block files passing through a FortiGate based on file type.

HTTP and FTP File Filtering is configurable in Web Filter profile.

File Filtering in Web Filter profile is based on file type (file's meta data) only, and not on file size or file content. You need to configure a DLP sensor to block files based on size or content such as SSN numbers, credit card numbers, or regexp.

File filtering only works on proxy mode policies.

Supported file types

The following file types are supported in File Filter and DLP profiles:

File Type Name	Description
.net	Match .NET files
7z	Match 7-zip files
activemime	Match activemime files
arj	Match arj compressed files
aspack	Match aspack files
avi	Match avi files
base64	Match base64 files
bat	Match Windows batch files
bin	Match bin files
binhex	Match binhex files
bmp	Match bmp files
bzip	Match bzip files
bzip2	Match bzip2 files
cab	Match Windows cab files
chm	Match Windows compiled HTML help files
class	Match class files
cod	Match cod files
crx	Match Chrome extension files
dmg	Match Apple disk image files
elf	Match elf files
exe	Match Windows executable files
flac	Match FLAC files
fsg	Match fsg files
gif	Match gif files
gzip	Match gzip files
hlp	Match Windows help files
hta	Match hta files
html	Match html files
iso	Match ISO archive files
jad	Match jad files
javascript	Match javascript files
jpeg	Match jpeg files
lzh	Match lzh compressed files
mach-o	Match Mach object files
mime	Match mime files
mov	Match mov files
mp3	Match mp3 files
mpeg	Match mpeg files
msc	Match msc files
msi	Match Windows Installer msi bzip files
msoffice	Match MS-Office files. For example, doc, xls, ppt, and so on.
msofficex	Match MS-Office XML files. For example, docx, xlsx, pptx, and so on.
pdf	Match pdf files
petite	Match petite files
png	Match png files
prc	Match prc files
rar	Match rar archives
rm	Match rm files
sis	Match sis files
tar	Match tar files
tiff	Match tiff files
torrent	Match torrent files
unknown*	Match unknown files
upx	Match upx files
uue	Match uue files
wav	Match wav files
wma	Match wma files
xar	Match xar archive files
xz	Match xz files
zip	Match zip files

^* This file type is only available in DLP profiles.

Example

In the following example, three file filters are used in the Web Filter profile:

1. Block PDFs from entering our leaving the network (filter1).
2. Log the download of some graphics file-types via HTTP (filter2).
3. Block executable files from leaving to the network over FTP (filter3).

To configure a file-type based web filter in the CLI:

config webfilter profile
    edit "webfilter-file-filter"
        config file-filter 
            set status enable
            set log enable
            set scan-archive-contents enable
            config entries 
                edit "filter1"
                    set comment "Block PDF files"
                    set protocol http ftp
                    set action block
                    set direction any
                    set encryption any
                    set file-type "pdf"
                next
                edit "filter2"
                    set comment "Log graphics files"
                    set protocol http
                    set action log
                    set direction incoming
                    set encryption any
                    set file-type "jpeg" "png" "gif"
                next
                edit "filter3"
                    set comment "Block upload of EXE files"
                    set protocol ftp
                    set action block
                    set direction outgoing
                    set encryption any
                    set file-type "exe"
                next
            end
        end
    next
end

After configuring file filters in Web Filter profile, apply it to a firewall policy:

config firewall policy
    edit 1
        set name "client-to-internet"
        set srcintf "dmz"
        set dstintf "wan1"
        set srcaddr "all"
        set dstaddr "all"
        set action accept
        set schedule "always"
        set service "ALL"
        set utm-status enable
        set utm-inspection-mode proxy
        set logtraffic all
        set webfilter profile "webfilter-filefilter"
        set profile-protocol-options "protocol"
        set ssl-ssh-profile "protocols"
        set nat enable
    next
end

To view the file filter logs:

# execute log filter category utm-file-filter
# execute log display 

File filter block action:

1: date=2020-06-25 time=10:10:38 logid="1900064000" type="utm" subtype="file-filter" eventtype="file-filter" level="warning" vd="root" eventtime=1593047438715790048 tz="+0900" policyid=1 sessionid=206159 srcip=10.0.0.20 srcport=46172 srcintf="port1" srcintfrole="lan" dstip=10.0.10.20 dstport=80 dstintf="wan1" dstintfrole="wan" proto=6 service="HTTP" profile="default" direction="incoming" action="blocked" url="http://www.fortitest.jp/download/test.pdf" hostname="www.fortitest.jp" agent="curl/7.58.0" filtername="test" filename="test.pdf" filesize=17556 filetype="pdf" msg="File was blocked by file filter."

File filter log action:

2: date=2019-03-19 time=10:48:23 logid="0346012672" type="utm" subtype="file-filter" eventtype="file-filter" level="notice" vd="vd1" eventtime=1548442102 policyid=1 sessionid=521 srcip=10.1.100.22 srcport=52894 srcintf="dmz" srcintfrole="undefined" dstip=172.16.200.55 dstport=80 dstintf="wan1" dstintfrole="undefined" proto=6 service="HTTP" hostname="172.16.200.55" profile="webfilter-filefilter" action="passthrough" reqtype="direct" url="/app_data/park.jpg" sentbyte=0 rcvdbyte=0 direction="incoming" filename="park.jpg" filtername="filter2" filetype="jpeg" msg="File was detected by file filter."

To configure a file-type based web filter in the GUI:

1. Go to Security Profiles > Web Filter.
2. Click Create New or select an existing profile and click Edit.

   

3. Enable File Filter.
4. Enable Log and Scan Archived Contents.
5. In the File Filter table, click Create New.
6. Configure the filters:
   1. filter1 blocks PDFs from entering our leaving the network .

      

   2. filter2 logs the download of some graphics file-types via HTTP .

      

   3. filter3 blocks EXE files from leaving to the network over FTP .

      

7. Click OK.
8. Add the new web filter profile to a firewall policy.
9. To see if there are file filter logs, go to VDOM > Log & Report > Forward Traffic. Select an entry and view the Log Details. The number of file filter logs for that entry is listed in the Other category.

   

   File filter logs can only be viewed in the CLI.