DNS Zone

The global DNS infrastructure is organized as a series of hierarchical DNS zones. The root zone hosts a number of global and country TLDs, which in turn host further zones that are delegated to their customers. Each organization that controls a zone can delegate parts of its namespace to other zones. In this test we perform detailed inspection of a DNS zone, but only if the host being tested matches the zone.

Nameserver Names

Nameservers can be referred to by name and by address. In this section we show the names, which can appear in the NS records, the referrals from the parent zone, and the SOA record. In some situations, servers from the parent zone respond authoritatively, in which case we will include them in the list as well.

Nameserver Addresses

This section shows the configuration of all discovered nameservers by their IP address. To find all applicable nameservers, we inspect the parent zone nameservers for names and glue and then the tested zone nameservers for NS records. We then resolve all discovered names to IP addresses. Finally, we test each address individually.

Start of Authority (SOA) Record

Start of Authority (SOA) records contain administrative information pertaining to one DNS zone, especially the configuration that's used for zone transfers between the primary nameserver and the secondaries. Only one SOA record should exist, with all nameservers providing the same information.

Backing DNS Queries

Below are all DNS queries we submitted during the zone inspection.

DNS Records

Correctly functioning name servers are necessary to hold and distribute information that's necessary for your domain name to operate correctly. Examples include converting names to IP addresses, determining where email should go, and so on. More recently, the DNS is being used to communicate email and other security policies.

DNS Records

These are the results of individual DNS queries against your nameserver for common resource record types.

Backing DNS Queries

Below are all DNS queries we submitted while inspecting the resource records.

DNSSEC

DNSSEC is an extension of the DNS protocol that provides cryptographic assurance of the authenticity and integrity of responses; it's intended as a defense against network attackers who are able to manipulate DNS to redirect their victims to servers of their choice. DNSSEC is controversial, with the industry split largely between those who think it's essential and those who believe that it's problematic and unnecessary.

Useful DNSSEC Tools

• Test tutanota.com @ DNSViz
• Test tutanota.com @ DNSSEC Analyzer (Verisign Labs)
• Zonemaster (iiS and AFNIC)

Certification Authority Authorization

CAA (RFC 8659) is a new standard that allows domain name owners to restrict which CAs are allowed to issue certificates for their domains. This can help to reduce the chance of misissuance, either accidentally or maliciously. In September 2017, CAA became mandatory for CAs to implement.

Email (SMTP)

An internet hostname can be served by zero or more mail servers, as specified by MX (mail exchange) DNS resource records. Each server can further resolve to multiple IP addresses, for example to handle IPv4 and IPv6 clients. Thus, in practice, hosts that wish to receive email reliably are supported by many endpoint.

220 mail.w11.tutanota.de ESMTP Tutanota

EHLO outbound.hardenize.com
250-mail.w11.tutanota.de
250-PIPELINING
250-SIZE 36700160
250-ETRN
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 CHUNKING

STARTTLS
220 2.0.0 Ready to start TLS

220 w4.tutanota.de ESMTP Tutanota

EHLO outbound.hardenize.com
250-w4.tutanota.de
250-PIPELINING
250-SIZE 36700160
250-ETRN
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 CHUNKING

STARTTLS
220 2.0.0 Ready to start TLS

220 w1.tutanota.de ESMTP Tutanota

EHLO outbound.hardenize.com
250-w1.tutanota.de
250-PIPELINING
250-SIZE 36700160
250-ETRN
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 CHUNKING

STARTTLS
220 2.0.0 Ready to start TLS

Email TLS (SMTP)

Transport Layer Security (TLS) is the most widely used encryption protocol on the Internet. In combination with valid certificates, servers can establish trusted communication channels even with users who have never visited them before. Network attackers can't uncover what is being communicated, even when they can see all the traffic.

Email Certificates (SMTP)

A certificate is a digital document that contains a public key, some information about the entity associated with it, and a digital signature from the certificate issuer. It’s a mechanism that enables us to exchange, store, and use public keys. Being able to reliably verify the identity of a remote server is crucial in order to achieve secure encrypted communication.

Certificate #1  Cached

Leaf certificate mail.tutanota.de
Issuer: Sectigo
Not Before: 17 Jul 2023 00:00:00 UTC
Not After: 10 Aug 2024 23:59:59 UTC (expires in 3 months 23 days)
Key: RSA 2048 bits
Signature: SHA256withRSA
 View details

Names	mail.tutanota.de www.mail.tutanota.de
Subject DN	CN=mail.tutanota.de
Subject Key Identifier	254491b7bf73e3811e1288c36bf727ac25f6653e
Serial	e66fca2de17820afad51a24abb32d901
Not Before	17 Jul 2023 00:00:00 UTC
Not After	10 Aug 2024 23:59:59 UTC
Validity period	391 days
Key Usage	digitalSignature, keyEncipherment
Extended Key Usage	serverAuth, clientAuth
Must Staple	No
Issuer
Issuer DN	CN=Sectigo RSA Domain Validation Secure Server CA, O=Sectigo Limited, L=Salford, ST=Greater Manchester, C=GB
Certification Authority	Sectigo
Validation Type	Domain Validation (DV)
Authority Key Identifier	keyid:8d8c5ec454ad8ae177e99bf99b05e1b8018d61e1
Parent Certificate	http://crt.sectigo.com/SectigoRSADomainValidationSecureServerCA.crt
OCSP	http://ocsp.sectigo.com
Certificate Transparency
Signed Certificate Timestamps	17 Jul 2023 23:46:02 UTC | Google 'Xenon2024' log | Qualified 17 Jul 2023 23:46:02 UTC | Cloudflare 'Nimbus2024' Log | Qualified 17 Jul 2023 23:46:02 UTC | Google 'Argon2024' log | Qualified
Fingerprints
SHA1	d6ffdddb4bd4b88ded21fc85caf7264f99590836
SHA256	36be6c83a1404577f0ef1054ef6a9ca845387fb87e2714156a8c67fc1d515aaf
SPKI SHA256	cfef7354b5c6b816646c39f9423d4a05ca726645ec040bf5268de8f377da7612

Analysis

Good

Strong private key

Good. The private key associated with this certificate is secure.

Good

Strong signature algorithm

Good. This certificate uses a strong signature algorithm.

Good

Certificate matches hostname

Good. The provided certificate matches the expected hostnames.

Good

Certificate dates match

Good. The certificate is valid for use at this point of time.

Good

Certificate has not been revoked

Good. This certificate has not been revoked.

Good

Certificate satisfies Apple's CT compliance requirements

Good. This certificate satisfies Apple's CT requirements at present.

Certificate Chain

Leaf certificate

mail.tutanota.de | 36be6c8
Not After: 10 Aug 2024 23:59:59 UTC (expires in 3 months 23 days)
Authentication: RSA 2048 bits (SHA256withRSA)
 View details

Names	mail.tutanota.de www.mail.tutanota.de
Subject DN	CN=mail.tutanota.de
Subject Key Identifier	254491b7bf73e3811e1288c36bf727ac25f6653e
Serial	e66fca2de17820afad51a24abb32d901
Not Before	17 Jul 2023 00:00:00 UTC
Not After	10 Aug 2024 23:59:59 UTC
Validity period	391 days
Key Usage	digitalSignature, keyEncipherment
Extended Key Usage	serverAuth, clientAuth
Must Staple	No
Issuer
Issuer DN	CN=Sectigo RSA Domain Validation Secure Server CA, O=Sectigo Limited, L=Salford, ST=Greater Manchester, C=GB
Certification Authority	Sectigo
Validation Type	Domain Validation (DV)
Authority Key Identifier	keyid:8d8c5ec454ad8ae177e99bf99b05e1b8018d61e1
Parent Certificate	http://crt.sectigo.com/SectigoRSADomainValidationSecureServerCA.crt
OCSP	http://ocsp.sectigo.com
Certificate Transparency
Signed Certificate Timestamps	17 Jul 2023 23:46:02 UTC | Google 'Xenon2024' log | Qualified 17 Jul 2023 23:46:02 UTC | Cloudflare 'Nimbus2024' Log | Qualified 17 Jul 2023 23:46:02 UTC | Google 'Argon2024' log | Qualified
Fingerprints
SHA1	d6ffdddb4bd4b88ded21fc85caf7264f99590836
SHA256	36be6c83a1404577f0ef1054ef6a9ca845387fb87e2714156a8c67fc1d515aaf
SPKI SHA256	cfef7354b5c6b816646c39f9423d4a05ca726645ec040bf5268de8f377da7612

Intermediate certificate

Sectigo RSA Domain Validation Secure Server CA | 7fa4ff6
Not After: 31 Dec 2030 23:59:59 UTC (expires in 6 years 8 months)
Authentication: RSA 2048 bits (SHA384withRSA)
 View details

Subject DN	CN=Sectigo RSA Domain Validation Secure Server CA, O=Sectigo Limited, L=Salford, ST=Greater Manchester, C=GB
Subject Key Identifier	8d8c5ec454ad8ae177e99bf99b05e1b8018d61e1
Serial	7d5b5126b476ba11db74160bbc530da7
Not Before	02 Nov 2018 00:00:00 UTC
Not After	31 Dec 2030 23:59:59 UTC
Key Usage	digitalSignature, keyCertSign, cRLSign
Extended Key Usage	serverAuth, clientAuth
Issuer
Issuer DN	CN=USERTrust RSA Certification Authority, O=The USERTRUST Network, L=Jersey City, ST=New Jersey, C=US
Certification Authority	Sectigo
Validation Type	Not Applicable
Authority Key Identifier	keyid:5379bf5aaa2b4acf5480e1d89bc09df2b20366cb
Parent Certificate	http://crt.usertrust.com/USERTrustRSAAddTrustCA.crt
CRL	http://crl.usertrust.com/USERTrustRSACertificationAuthority.crl
OCSP	http://ocsp.usertrust.com
CA certificate	Yes (pathlen 0)
Fingerprints
SHA1	33e4e80807204c2b6182a3a14b591acd25b5f0db
SHA256	7fa4ff68ec04a99d7528d5085f94907f4d1dd1c5381bacdc832ed5c960214676
SPKI SHA256	e1ae9c3de848ece1ba72e0d991ae4d0d9ec547c6bad1dddab9d6beb0a7e0e0d8

Intermediate certificate

USERTrust RSA Certification Authority | 68b9c76
Not After: 31 Dec 2028 23:59:59 UTC (expires in 4 years 8 months)
Authentication: RSA 4096 bits (SHA384withRSA)
 View details

Subject DN	CN=USERTrust RSA Certification Authority, O=The USERTRUST Network, L=Jersey City, ST=New Jersey, C=US
Subject Key Identifier	5379bf5aaa2b4acf5480e1d89bc09df2b20366cb
Serial	3972443af922b751d7d36c10dd313595
Not Before	12 Mar 2019 00:00:00 UTC
Not After	31 Dec 2028 23:59:59 UTC
Key Usage	digitalSignature, keyCertSign, cRLSign
Issuer
Issuer DN	CN=AAA Certificate Services, O=Comodo CA Limited, L=Salford, ST=Greater Manchester, C=GB
Certification Authority	Sectigo
Validation Type	Not Applicable
Authority Key Identifier	keyid:a0110a233e96f107ece2af29ef82a57fd030a4b4
CRL	http://crl.comodoca.com/AAACertificateServices.crl
OCSP	http://ocsp.comodoca.com
CA certificate	Yes (pathlen unlimited)
Fingerprints
SHA1	d89e3bd43d5d909b47a18977aa9d5ce36cee184c
SHA256	68b9c761219a5b1f0131784474665db61bbdb109e00f05ca9f74244ee5f5f52b
SPKI SHA256	c784333d20bcd742b9fdc3236f4e509b8937070e73067e254dd3bf9c45bf4dde

Root certificate

AAA Certificate Services | d7a7a0f
Not After: 31 Dec 2028 23:59:59 UTC (expires in 4 years 8 months)
Authentication: RSA 2048 bits (SHA1withRSA)
 View details

Subject DN	CN=AAA Certificate Services, O=Comodo CA Limited, L=Salford, ST=Greater Manchester, C=GB
Subject Key Identifier	a0110a233e96f107ece2af29ef82a57fd030a4b4
Serial	1
Not Before	01 Jan 2004 00:00:00 UTC
Not After	31 Dec 2028 23:59:59 UTC
Key Usage	keyCertSign, cRLSign
Issuer
Issuer DN	CN=AAA Certificate Services, O=Comodo CA Limited, L=Salford, ST=Greater Manchester, C=GB
Certification Authority	Sectigo
Validation Type	Self-signed
CRL	http://crl.comodoca.com/AAACertificateServices.crl http://crl.comodo.net/AAACertificateServices.crl
CA certificate	Yes (pathlen unlimited)
Fingerprints
SHA1	d1eb23a46d17d68fd92564c2f1f1601764d8e349
SHA256	d7a7a0fb5d7e2731d771e9484ebcdef71d5f0c3e0a2948782bc83ee0ea699ef4
SPKI SHA256	bd153ed7b0434f6886b17bce8bbe84ed340c7132d702a8f4fa318f756ecbd6f3

Email DANE (SMTP)

DNS-based Authentication of Named Entities (DANE) is a bridge between DNSSEC and TLS. In one possible scenario, DANE can be used for public key pinning, building on an existing publicly-trusted certificate. In another approach, it can be used to completely bypass the CA ecosystem and establish trust using DNSSEC alone.

SPF

Sender Policy Framework (SPF) is a protocol that allows domain name owners to control which internet hosts are allowed to send email on their behalf. This simple mechanism can be used to reduce the effect of email spoofing and cut down on spam.

DMARC

Domain-based Message Authentication, Reporting, and Conformance (DMARC) is a scalable mechanism by which a mail-originating organization can express domain-level policies and preferences for message validation, disposition, and reporting, that a mail-receiving organization can use to improve mail handling.

MTA Strict Transport Security

SMTP Mail Transfer Agent Strict Transport Security (MTA-STS) is a mechanism enabling mail service providers to declare their ability to receive Transport Layer Security (TLS) secure SMTP connections, and to specify whether sending SMTP servers should refuse to deliver to MX hosts that do not offer TLS with a trusted server certificate.

SMTP TLS Reporting

SMTP TLS Reporting (RFC 8460), or TLS-RPT for short, describes a reporting mechanism and format by which systems sending email can share statistics and specific information about potential failures with recipient domains. Recipient domains can then use this information to both detect potential attacks and diagnose unintentional misconfigurations. TLS-RPT can be used with DANE or MTA-STS.

HTTP (80)

To observe your HTTP implementation, we submit a request to the homepage of your site on port 80, follow all redirections (even when they take us to other domain names), and record the returned HTTP headers.

URL: http://tutanota.com/

URL: http://www.tutanota.com/

HTTP (443)

To observe your HTTPS implementation, we submit a request to the homepage of your site on port 443, follow all redirections (even when they take us to other domain names), and record the returned HTTP headers. We use the most recent set of headers returned from the tested hostname for further tests such as HSTS and HPKP.

URL: https://tutanota.com/

URL: https://www.tutanota.com/

WWW TLS

Transport Layer Security (TLS) is the most widely used encryption protocol on the Internet. In combination with valid certificates, servers can establish trusted communication channels even with users who have never visited them before. Network attackers can't uncover what is being communicated, even when they can see all the traffic.

WWW Certificates

A certificate is a digital document that contains a public key, some information about the entity associated with it, and a digital signature from the certificate issuer. It’s a mechanism that enables us to exchange, store, and use public keys. Being able to reliably verify the identity of a remote server is crucial in order to achieve secure encrypted communication.

DANE (443)

DNS-based Authentication of Named Entities (DANE) is a bridge between DNSSEC and TLS. In one possible scenario, DANE can be used for public key pinning, building on an existing publicly-trusted certificate. In another approach, it can be used to completely bypass the CA ecosystem and establish trust using DNSSEC alone.

Cookies

Cookies are small chunks of text that are sent between your browser and a website. They are often essential to the operation of the site and sometimes contain sensitive information. Session cookies sent from secure sites must be explicitly marked as secure to prevent being obtained by active network attackers.

Mixed Content

On virtually all web sites, HTML markup, images, style sheets, JavaScript, and other page resources arrive not only over multiple connections but possibly from multiple servers and sites spread across the entire Internet. For a page to be properly encrypted, it’s necessary that all the content is retrieved over HTTPS. In practice, that’s very often not the case, leading to mixed content security problems.

HTTP Strict Transport Security

HTTP Strict Transport Security (HSTS) vastly improves security of the network encryption layer. With HSTS enabled, browsers no longer allow clicking through certificate warnings errors, which are typically trivial to exploit. Additionally, they will no longer submit insecure (plaintext) requests to the site in question, even if asked.

HTTP Public Key Pinning

HTTP Public Key Pinning (HPKP) enables site operators to restrict which certificates are considered valid for their domain names. With a valid HPKP configuration, sites can defeat man in the middle (MITM) attacks using fraudulent or misissued certificates. HPKP is an advanced feature, suitable for use by only high-profile web sites.

Content Security Policy

Content Security Policy (CSP) is a security mechanism that allows web sites control how browsers process their pages. In essence, sites can restrict what types of resources are loaded and from where. CSP policies can be used to defend against cross-site scripting, prevent mixed content issues, as well as report violations for investigation.

Subresource Integrity

Subresource Integrity (SRI) is a new standard that enables browsers to verify the integrity of embedded page resources (e.g., scripts and stylesheets) when they are loaded from third-party web sites. With SRI deployed, remote resources can be used safely, without fear of them being modified by malicious parties.

Expect CT

Expect-CT is a deprecated response HTTP header designed to enable web sites to monitor problems related to their Certificate Transparency (CT) compliance. Should any CT issues arise, browsers that supported this header will submit reports to the specified reporting endpoint. Chrome was the browser that introduced support for this response header, but later deprecated it and removed it in version 107.

Frame Options

The X-Frame-Options header controls page framing, which occurs when a page is incorporated into some other page, possibly on a different site. If framing is allowed, attackers can employ clever tricks to make victims perform arbitrary actions on your site; they do this by showing their web site while forwarding the victim's clicks to yours.

XSS Protection

Some browsers ship with so-called XSS Auditors, built-in defenses against XSS. Although these defenses work against simple reflective XSS attacks, they can be abused by skillful attackers to add weaknesses to otherwise secure web sites. These dangers are present in both filtering and blocking modes. At this time, the Safari browser ships with its XSS defenses enabled by default. For this reason, the best approach is to explicitly disable this functionality.

Content Type Options

Some browsers use a technique called content sniffing to override response MIME types provided by HTTP servers and interpret responses as something else (usually HTML). This behavior, which could potentially lead to security issues, should be disabled by attaching an X-Content-Type-Options header to all responses.