253
votes
Accepted
Why is "fhepfcelehfcepfffacacacacacacabn" a top DNS query from my devices?
That domain is an encoded form of the string "WORKGROUP". It is using a variant of hex encoding that uses the letters A-P, instead of the numbers 0-9 followed by A-F.
$ echo ...
- 846
126
votes
Accepted
Did I just get DNS Hijacked?
Yes, your router's primary DNS entry was pointed to a rogue DNS server to make devices in your network resolve apple.com and other domains to phishing sites instead. The router possibly got ...
- 44.6k
74
votes
Is my Windows 10 machine experiencing DNS poisoning? I keep getting Chinese IP addresses when connecting to a U.S. government domain
Content Delivery Network
This is probably part of a Content Delivery Network with a lot of political issues to consider.
If you try dig www.whitehouse.gov a, underneath the answer section you'll ...
- 22.6k
69
votes
Accepted
More than three domains hosted on the same IP address
This is not a sign of a problem for your server. There's an important detail here, which is:
104.27.182.86 is not your server. That IP belongs to cloudflare.
Cloudflare provides a large number of ...
- 30.9k
58
votes
Accepted
What stops someone from just redirecting a HTTPS connection to a HTTP version of the site?
The decision on whether to use HTTP or HTTPS is the client's.
If the user goes directly to http://example.com, an attacker could simply hijack that connection and perform a man-in-the-middle attack. ...
- 135k
56
votes
Accepted
Why don't browser DNS caches mitigate DDOS attacks on DNS providers?
You are correct that the DNS cache would mitigate against a nameserver being unavailable. It is extremely common to have a TTL of 5 minutes or lower. Hence, 5 minutes after the DDOS attack brought ...
- 1,201
52
votes
Accepted
Domain about to expire. Afraid that new owners will spread malware
Unless your freeware is somewhat popular or used by high-value targets, its usefulness for conducting supply chain attacks is probably limited. If the domain name enjoys good SEO, I would rather ...
- 7,847
51
votes
Accepted
How can changing your DNS protect your online privacy?
Essentially, it doesn't.
DNS servers let your computer look up where websites and other services are based on friendly names, by converting those to IP addresses. Your ISP provides this as a service, ...
- 27.4k
49
votes
Why don't browser DNS caches mitigate DDOS attacks on DNS providers?
A small design change to DNS caches could make a big difference. Most DNS caches remove an entry when the TTL expires. A cache could instead keep the entry, but mark it as expired. If a query comes in ...
- 33.4k
49
votes
Accepted
Is it possible for a name server provider to hijack MX records?
Yes, your registrar can hijack not only your MX records, but your entire DNS.
Not only that - but they can then proceed to intercept mail sent to your domain, get a valid CA-signed SSL certificate ...
- 22.7k
48
votes
How could a public DNS server return bad results?
How are they (ISP) achieving this, Are they really stealing and MITM ing the traffic of 8.8.8.8?
They probably simply redirect all packets with destination port 53 (i.e. DNS) to their own servers and ...
- 198k
44
votes
How do I run proper HTTPS on an Internal Network?
Certificate validation is done to make sure that the peer is the one you expect. Validating a server certificate in the browser is mainly done by checking that the hostname from the URL matches the ...
- 198k
41
votes
Accepted
Why is it better to use ports 20 and 53 as source ports when portscanning?
You guessed correctly.
According to the Nmap Reference Guide:
--source-port <portnumber>; -g <portnumber> (Spoof source port number)
One surprisingly common misconfiguration is to trust ...
- 3,592
37
votes
Accepted
How does a website know the DNS server a client uses?
This is a DNS resolution trick that could also be performed using non-http protocols but in this case is performed by using random hostnames and zero-pixel images via http.
Look at the source code on ...
- 14.2k
35
votes
Is my Windows 10 machine experiencing DNS poisoning? I keep getting Chinese IP addresses when connecting to a U.S. government domain
Well, I've installed Wireshark and applied a DNS filter to see what was happening. When I do the nslookup from Windows to whitehouse.gov I can see in Wireshark that it is appending (without showing it ...
- 761
35
votes
Why is "fhepfcelehfcepfffacacacacacacabn" a top DNS query from my devices?
Update: This answer by Miles is a better insight, the explanation given by NextDNS support seems wrong.
I contacted NextDNS support asking for more details and they said this is Google Chrome testing ...
- 852
32
votes
Accepted
Why don't browsers check CAA records to help ensure a certificate is valid?
I just found the answer in RFC 6844, DNS Certification Authority Authorization (CAA) Resource Record:
A set of CAA records describes only current grants of authority to
issue certificates for the ...
- 737
32
votes
More than three domains hosted on the same IP address
This is perfectly normal. There is a big shortage of IPv4 addresses. In fact, we should have run out of them a long time ago. But since so much infrastructure is based on IPv4, it keeps getting "...
31
votes
Does DNS allow third parties to register subdomains?
Short answer: No, third parties can't register a subdomain without authorization from the owner of the domain.
DNS is a hierarchical system, ordered from right to left in the hostname. Whoever has a ...
- 2,703
31
votes
Why is DNS-over-HTTPS such a big security nightmare compared to DNS-over-TLS?
Again, it's all about the threat model!
Technologies are just technologies and can be used both for good and for evil. DNS over HTTPS (DoH) intends to solve the privacy concerns there are with ...
- 18.7k
29
votes
Accepted
Does DNS allow third parties to register subdomains?
Welcome to Security!
The case of educational/government intitutions is a particular case of subdomaining. Basically ICANN, who rules the Internet top names, delegated maangement of the .au TLD to ...
- 5,406
29
votes
Accepted
Is a global DNS record a security risk for phpMyAdmin?
This would qualify as 'Security through Obscurity' and offers little to no protection whatsoever.
The /etc/hosts file is NOT DNS; it's the precursor of DNS and anyone can change their own records in ...
- 8,713
22
votes
Accepted
What does my ISP see if I change my DNS server?
So, I think, that when I type certain URL in my browser (for example https://google.com) I send request through ISP to ISP DNS and my provider gets response (ip of google.com) and goes by this IP and ...
- 198k
21
votes
Did I just get DNS Hijacked?
It's obvious that someone changed DNS entries inside your router, probably using default credentials. You should go with factory reset, update your firmware, change default credentials and disable ...
- 10.2k
21
votes
How could a public DNS server return bad results?
unfortunately they are not doing so!
They are doing so, and your typescript shows it happening, with nslookup querying that IP address and getting answers from it.
Your confusion stems in part from ...
- 701
21
votes
Domain about to expire. Afraid that new owners will spread malware
Cost makes a big difference. Some people think keeping a domain means spending hundreds of dollars a year because "that's what we've always paid", but that really is not the case.
If the ...
20
votes
Should OS information be in DNS?
The naming conventions of computers has long been a divisive topic and often the security of a network needs to be put up against the manageability of an environment. I have worked in environments ...
- 9,227
19
votes
How do I run proper HTTPS on an Internal Network?
"Use public certs, but for internal addresses."
This option works quite well, that's what we do.
You can actually do HTTP validation, the certificate does not include the IP address, just ...
- 311
19
votes
Does DNS allow third parties to register subdomains?
The DNS registrars only care about the registration of the primary domain, i.e. example.com. They don't care about any sub-domains like www.example.com or www.math.example.com and similar. These are ...
- 198k
19
votes
Accepted
Hijacking stale DNS entry to point to your own website
This is a subdomain takeover.
They typically happen in one of 2 ways:
You have an A record pointing to an IP address that no longer exists and an attacker can gain control of the IP address in ...
- 30.9k
Only top scored, non community-wiki answers of a minimum length are eligible