Botnet C&C domain blocking

FortiGuard Service continually updates the botnet C&C domain list. The botnet C&C domain blocking feature can block the botnet website access at the DNS name resolving stage. This provides additional protection for your network.

A DNS filter profile can be applied in a policy to scan DNS traffic traversing the FortiGate (see Configuring a DNS filter profile), or applied on the DNS server interface (see Applying DNS filter to FortiGate DNS server).

To configure botnet C&C domain blocking in the GUI:

1. Go to Security Profiles > DNS Filter and click Create New, or edit an existing profile.
2. Enable Redirect botnet C&C requests to Block Portal.
3. Optionally, click the botnet package link. The Botnet C&C Domain Definitions pane opens, which displays the latest list.

   

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

To configure botnet C&C domain blocking in the CLI:

config dnsfilter profile
   edit "demo"
      set comment ''
      config domain-filter
         unset domain-filter-table
      end
      config ftgd-dns
         set options error-allow
         config filters
            ...
         end
      end
      set log-all-domain enable
      set sdns-ftgd-err-log enable
      set sdns-domain-log enable
      set block-action block 
      set block-botnet enable
      set safe-search enable
      set redirect-portal 208.91.112.55
      set youtube-restrict strict
   next
end

Verifying the logs

Select a botnet domain from that list. From your internal network PC, use a command line tool, such as dig or nslookup, to send a DNS query to traverse the FortiGate. For example:

#dig canind.co
;; ->>HEADER<<- opcode: QUERY; status: NOERROR; id: 997
;; Flags: qr rd; QUERY: 1; ANSWER: 1; AUTHORITY: 0; ADDITIONAL: 0

;; QUESTION SECTION:
;; canind.co.                   IN      A

;; ANSWER SECTION:
canind.co.              60      IN      A       208.91.112.55

;; Received 43 B
;; Time 2019-04-05 09:55:21 PDT
;; From 172.16.95.16@53(UDP) in 0.3 ms

The botnet domain query was blocked and redirected to the portal IP (208.91.112.55) .

To check the DNS filter log in the GUI:

1. Go to Log & Report > DNS Query to view the DNS query blocked as a botnet domain.

   

To check the DNS filter log in the CLI:

(vdom1) # execute log filter category utm-dns

(vdom1) # execute log display 
2 logs found.
2 logs returned.

1: date=2019-04-04 time=16:43:59 logid="1501054601" type="utm" subtype="dns" eventtype="dns-response" level="warning" vd="vdom1" eventtime=1554421439 policyid=1 sessionid=14135 srcip=10.1.100.18 srcport=57447 srcintf="port10" srcintfrole="undefined" dstip=172.16.95.16 dstport=53 dstintf="port9" dstintfrole="undefined" proto=17 profile="demo" xid=24339 qname="canind.co" qtype="A" qtypeval=1 qclass="IN" msg="Domain was blocked by dns botnet C&C" action="redirect" botnetdomain="canind.co"

2: date=2019-04-04 time=16:43:59 logid="1500054000" type="utm" subtype="dns" eventtype="dns-query" level="information" vd="vdom1" eventtime=1554421439 policyid=1 sessionid=14135 srcip=10.1.100.18 srcport=57447 srcintf="port10" srcintfrole="undefined" dstip=172.16.95.16 dstport=53 dstintf="port9" dstintfrole="undefined" proto=17 profile="demo" xid=24339 qname="canind.co" qtype="A" qtypeval=1 qclass="IN"

Botnet C&C IPDB blocking

FortiOS also maintains a botnet C&C IP address database (IPDB). If a DNS query response IP address (resolved IP address) matches an entry inside the botnet IPDB, this DNS query is blocked by the DNS filter botnet C&C.

To view the botnet IPDB list in the CLI:

(global) # diagnose sys botnet list 9000 10
9000. proto=TCP ip=103.228.28.166, port=80, rule_id=7630075, name_id=3, hits=0
9001. proto=TCP ip=5.9.32.166, port=481, rule_id=4146631, name_id=7, hits=0
9002. proto=TCP ip=91.89.44.166, port=80, rule_id=48, name_id=96, hits=0
9003. proto=TCP ip=46.211.46.166, port=80, rule_id=48, name_id=96, hits=0
9004. proto=TCP ip=77.52.52.166, port=80, rule_id=48, name_id=96, hits=0
9005. proto=TCP ip=98.25.53.166, port=80, rule_id=48, name_id=96, hits=0
9006. proto=TCP ip=70.120.67.166, port=80, rule_id=48, name_id=96, hits=0
9007. proto=TCP ip=85.253.77.166, port=80, rule_id=48, name_id=96, hits=0
9008. proto=TCP ip=193.106.81.166, port=80, rule_id=48, name_id=96, hits=0
9009. proto=TCP ip=58.13.84.166, port=80, rule_id=48, name_id=96, hits=0

Select an IP address from the IPDB list and use a reverse lookup service to find its corresponding domain name. From your internal network PC, use a command line tool, such as dig or nslookup, to query this domain and verify that it is blocked by the DNS filter botnet C&C. For example:

# dig cpe-98-25-53-166.sc.res.rr.com
;; ->>HEADER<<- opcode: QUERY; status: NOERROR; id: 35135
;; Flags: qr rd; QUERY: 1; ANSWER: 1; AUTHORITY: 0; ADDITIONAL: 0

;; QUESTION SECTION:
;; cpe-98-25-53-166.sc.res.rr.com.              IN      A

;; ANSWER SECTION:
cpe-98-25-53-166.sc.res.rr.com. 60      IN      A       208.91.112.55

;; Received 64 B
;; Time 2019-04-05 11:06:47 PDT
;; From 172.16.95.16@53(UDP) in 0.6 ms

Since the resolved IP address matches the botnet IPDB, the query was blocked and redirected to the portal IP (208.91.112.55) .

To check the DNS filter log in the GUI:

1. Go to Log & Report > DNS Query to view the DNS query blocked by botnet C&C IPDB.

   

To check the DNS filter log in the CLI:

(global) # execute log filter category utm-dns

(global) # execute log display
2 logs found.
2 logs returned.
			
1: date=2019-04-05 time=11:06:48 logid="1501054600" type="utm" subtype="dns" eventtype="dns-response" level="warning" vd="vdom1" eventtime=1554487606 policyid=1 sessionid=55232 srcip=10.1.100.18 srcport=60510 srcintf="port10" srcintfrole="undefined" dstip=172.16.95.16 dstport=53 dstintf="port9" dstintfrole="undefined" proto=17 profile="demo" xid=16265 qname="cpe-98-25-53-166.sc.res.rr.com" qtype="A" qtypeval=1 qclass="IN" ipaddr="93.184.216.34" msg="Domain was blocked by dns botnet C&C" action="redirect" botnetip=98.25.53.166

2: date=2019-04-05 time=11:06:48 logid="1500054000" type="utm" subtype="dns" eventtype="dns-query" level="information" vd="vdom1" eventtime=1554487606 policyid=1 sessionid=55232 srcip=10.1.100.18 srcport=60510 srcintf="port10" srcintfrole="undefined" dstip=172.16.95.16 dstport=53 dstintf="port9" dstintfrole="undefined" proto=17 profile="demo" xid=16265 qname="cpe-98-25-53-166.sc.res.rr.com" qtype="A" qtypeval=1 qclass="IN"

To check botnet activity:

1. Go to Dashboard > Status and locate the Botnet Activity widget.

2. If you do not see the widget, click Add Widget, and add the Botnet Activity widget.