If you are seeing queries for this domain, than you are likely participating in DNS Amplification attacks and your DNS server is probably reachable from the internet and has recursion enabled.
If you are seeing responses for this domain.. unlucky. You are currently beeing DDOS-ed! Good luck.
IPtables:
There are two iptable rules available. If your distribution supports Iptables 'u32' module pick this one, otherwise use the 'string' rule.
U32:
iptables --insert INPUT -p udp --dport 53 -m u32 --u32 "0x28&0xFFDFDFDF=0x07474552 && 0x2c&0xDFDFDFFF=0x44415233 && 0x30&0xFFDFDFFF=0x02525500" -j DROP -m comment --comment "DROP DNS Q gerdar3.ru"
More U32 rules can be found here:
https://github.com/smurfmonitor/dns-iptables-rules/blob/master/domain-blacklist.txt
String:
iptables --insert INPUT -p udp --dport 53 -m string --from 40 --to 52 --algo bm --hex-string '|076765726461723302727500|' -j DROP -m comment --comment "DROP DNS Q gerdar3.ru"
More Iptables rules for the STRING module can be found here:
https://github.com/smurfmonitor/dns-iptables-rules/blob/master/domain-blacklist-string.txt
Source:
54.230.84.31
Name server:
;; ANSWER SECTION:
gerdar3.ru. 599 IN NS ns1.spaceweb.ru.
gerdar3.ru. 599 IN NS ns2.spaceweb.ru.
Response:
A 13
MX 28
NS 2
SOA 1
TXT 11
Rsize 4006
Whois
% By submitting a query to RIPN's Whois Service
% you agree to abide by the following terms of use:
% http://www.ripn.net/about/servpol.html#3.2 (in Russian)
% http://www.ripn.net/about/en/servpol.html#3.2 (in English).
domain: GERDAR3.RU
nserver: ns1.spaceweb.ru.
nserver: ns2.spaceweb.ru.
state: REGISTERED, DELEGATED, VERIFIED
person: Private Person
registrar: R01-REG-RIPN
admin-contact: https://partner.r01.ru/contact_admin.khtml
created: 2014.02.08
paid-till: 2015.02.08
free-date: 2015.03.11
source: TCI
Last updated on 2014.02.11 03:51:37 MSK
Confirmed, I see these too. Trying DNS amplification is obvious.
ReplyDeleteI have created DNS-Blackhole zones for affected domains.Personally, I think your "iptables" approach to deal with this is wrong. But thanks for posting!
Can confirm our corporate network beein DDoSed with this RegEx. Our AntiDDoS HW solution is blockin it.
ReplyDelete