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 ...
- 866
125
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 ...
- 45.1k
73
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 ...
- 31.7k
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 ...
- 1,191
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 ...
- 8,465
50
votes
Is LetsEncrypt activity Public?
New certificates end up in certificate transparency logs which are visible to the public. This can be used to detect seemingly hidden domains, which are not linked from somewhere, might not be even ...
- 208k
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 ...
- 34.7k
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 ...
- 24k
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 ...
- 208k
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 ...
- 751
35
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 ...
- 787
34
votes
Why is "fhepfcelehfcepfffacacacacacacabn" a top DNS query from my devices?
Update: The explanation given by NextDNS support is wrong, see this answer by Miles instead.
I contacted NextDNS support asking for more details and they said this is Google Chrome testing internet ...
- 862
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 "...
32
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 ...
- 19.4k
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 ...
- 2,701
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 ...
- 5,418
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 ...
- 9,063
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 ...
- 208k
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
20
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 ...
- 321
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
20
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 ...
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 ...
- 208k
18
votes
Accepted
How can I look up a Certificate Authorities CAA record value?
The best way I can think of is asking the CAA record of issuers' domain. Most likely they have it setup for their own domains. I tried it with a few and it seems to work for some.
$ dig caa comodo.com
...
- 2,015
18
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 ...
- 31.7k
16
votes
Accepted
Why is DNS-over-HTTPS such a big security nightmare compared to DNS-over-TLS?
I've heard the argument against DNS-over-HTTPS that it is supposed to be a security nightmare for network defenders because it enables encrypted DNS over port 443, compared to DNS-over-TLS which goes ...
- 6,098
16
votes
Accepted
What happens if a DNS record points to non-controlled IP address?
what will be displayed in his browser?
Either an error message or the Twitter homepage. Your browser will connect to Twitter's web server, and request the page for foo.com. The webserver can either ...
- 34.4k
15
votes
Accepted
What's the difference between A and AAAA DNS records?
In DNS, we can have multiple answers and we called them Resource Records, shorten as RR.
Among the RR, there are A, AAAA, MX, NS,TXT,DS and many others. More details are available on this wiki page. ...
- 637
Only top scored, non community-wiki answers of a minimum length are eligible