Email encryption – A guide for implementation at SMBs

Email encryption – A guide for implementation at SMBs

Certificates, signed emails, symmetric and asymmetric encryption, S/MIME, TLS and PGP – for many who do not regularly deal with email encryption these terms are quite foreign. However, with the new basic data protection regulations (DSGVO) these terms have been pushed to the top of the to-do lists for many SMBs. Although, many companies lack the necessary knowledge to implement the new requirements in regards to the encryption of their email communication. In this article, Hornetsecurity aims to explain some of the basic terms and technologies around email encryption.

Asymmetric and symmetric email encryption – what are the differences?

If you take a closer look at asymmetric and symmetric email encryption you will very quickly discover that these two are fundamentally different. Essentially, they differ in the number and type of keys used.

Symmetric email encryption uses the same key to encrypt and decrypt the email. This means that the sender and recipient of an email share the same key. Thus, this procedure is very simple, but its security is essentially tied to the secrecy of the keys – if the key falls into the hands of a third party that person can decrypt the entire communication.

Asymmetric email encryption uses a total of four keys, one key pair each – a public and a private key per communication partner. The public key is accessible to everyone who wants to communicate and is transferred with the certificate exchange. It is used to encrypt the data, in our case, emails.

To decrypt the encrypted data again, the private key belonging to the public key is required. Although the key pair is mathematically interdependent and it’s practically impossible to calculate it.

S/MIME, PGP and TLS – what are the abbreviations?

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PGP and S/MIME are asymmetric encryption methods. Both procedures have a decisive advantage and disadvantage. The advantage is that the email provider of the sender and recipient also has no insight into the email. The disadvantage is that only the message is encrypted. The sender and recipient as well as the subject can still be read.

The main difference between email encryption with S/MIME and PGP is the issue of certificates. While PGP (also known as OpenPGP) is an open source solution in which everyone can create their own certificates, certification at S/MIME takes place via official certification authorities, the so-called Certificate Authorities (CA).

TLS differs fundamentally from email encryption with S/MIME or PGP. Here it’s not the email itself that is encrypted, but only the connection between the two communicating servers. This means that the email cannot be accessed during transport, but it is not encrypted on the respective mail servers.

How to implement email encryption – there is no “one” way

All roads lead to Rome – but which ones lead to legally compliant email encryption? In fact, there are several ways for companies to implement legally compliant email encryption. The most prominent are on-premise and cloud-based solutions.

With on-premise solutions, the emails are encrypted directly on site, i.e. at the companies themselves. The email encryption software can be purchased, rented or operated completely independently from an external provider. Although this procedure offers the company a high degree of transparency and decision-making freedom, it involves an administrative effort that should not be underestimated. The costs for maintenance and operation are also quite significant. Today, on-premise solutions are considered a thing of the past and are increasingly being replaced by modern cloud-based computing.

E-Mail-Verschlüsselung bei Hornetsecurity

Graphic: Email encryption using cloud computing (click to enlarge)

With the cloud-based computing alternative, also known as “Software as a Service” (SaaS) solution, the security provider relieves the company of all expenses, such as administrative and operational costs. All of the company’s email traffic is then handled by the security provider’s servers, including Hornetsecurity’s email encryption service. The route between the customer’s mail server and the service provider is protected by TLS. This solution is characterized by the elimination of administrative work for any particular company. However, to fully ensure secure email communication, TLS and S/MIME can and should be used simultaneously. This is the only way to encrypt the email itself and its transport route.

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With multiple levels of protection to be on the safe side

With multiple levels of protection to be on the safe side

Anti-virus solutions alone are not enough – but they still make sense

The world has become more complex, not only in politics and business but also in the field of IT security. Multi-layered defense measures are a must for companies if they want to effectively protect their IT infrastructure because cyber threats have also become much more versatile and professional. “Simple” solutions by themselves are no longer enough, yet still have their reason for being.

Until a few years ago it was relatively easy to organize the protection of your IT systems. And even today, there are still companies that rely on a few established defensive measures. Together with a firewall and a spam filter, classic AV solutions are still the standard to protect against intruders, and one of the main reasons this type of protection is generally accepted as a proven mechanism against malware. Antivirus products are highly automated and do not require extensive attention from IT administrators or security specialists, which saves money, time and effort.

Modern malware outwits classic AV products

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On the other hand, the discussion has been smoldering for some time as to whether anti-virus solutions are still effective against malware at all or perhaps do more harm than good and should therefore be abandoned. The fact is, classic products for defending against malware no longer offer adequate protection. Classic AV scanners fail to recognize all malware specimens and many specimens are not recognized at all, even after many weeks or even months.

Strengths and weaknesses in malware detection are widely distributed among the various AV providers. In addition, new types of cyber-attacks are making life increasingly difficult for classic AV scanners. Polymorphic viruses, e.g. in the form of ransomware, are evading signature-based detection mechanisms in slightly modified forms. Classic AV scanners have little or no chance against file-less attacks such as CEO fraud as these do not contain any suspicious objects for investigation.

Equally problematic are links in documents that can lead to downloads of malware. Companies that solely rely on the use of classic security solutions weigh themselves in false security. Nevertheless, the use of classic AV scanners is necessary and sensible.

Many defensive measures spoil the attacker’s success

Modern IT security solutions and suites are built on the principle of multiple protection with multiple defense methods and there are good reasons for employing multi-level protection. If the first protective measures complete part of the task in a relatively simple way, the powerful and more complex filters behind it are no longer so heavily loaded and thus perform better.

Subsequent security levels based on heuristic or behavior-based filter systems significantly improve detection performance and thus increase the chance of being spared damage by malware. These include services that detect hidden links in emails or attachments, analyze the behavior of malware in a sandbox, or hold back suspicious email attachments for a certain period of time and then check these attachments again with updated signatures.

Many companies have recognized this and rely on a multi-part defense strategy with several defensive lines in place. This way, they minimize the risk of experiencing a nasty surprise and becoming victims of a cyber-attack.

Additional information:

  1. Hornetsecurity Managed Spamfilter Service for companies
  2. Want to learn more about Advanced Threat Protection? Find out more now!.
  3. Do you already know the Hornetsecurity Knowledge Base? Click here for more information.
Malware Analysis and Defense

Malware Analysis and Defense

Third part of the multipart “Defense against malware”

The workstations of our malware analysts do not differ from others in Hornetsecurity’s offices, even though the Security Lab is referred to as a “laboratory”. Erlenmeyer flasks, test tubes and Bunsen burners are not to be found, but quite normal computers. The work is done virtually, in sandboxes or by analyzing the data traffic. Nevertheless, the importance of malware analysts should not be underestimated, as it ensures that Hornetsecurity’s defense systems are always as up-to-date as possible and maintain the highest quality standard.

But what is the procedure for analyzing malware? Usually there is a very large, continuous stream of data to analyze. The main task is to extract valuable information from the raw data, process it and make it “intelligent”. To this end, analysts use various tools and programs to answer specific questions: What are the objectives of malware? Which characteristics are typical for the investigated malware? Is there any evidence of the attacker(s)? Ideally, actions can be derived from the findings such as writing new filter rules or creating algorithms.

Two different types of analysis

Two ways of analyzing malware are presented in more detail here. In static analysis, the code itself is viewed without executing the malware, while in dynamic analysis, the behavior of the malicious code is tracked in a secure environment.

In the static analysis, the analysts break down the malware to the smallest detail in order to draw conclusions from the code itself. For example, significant strings are extracted or shell scripts are started and further results are generated with disassemblers. Here you can find information on the activities of the malware and which features it shows, the so-called Indicators of Compromise (IoC). Based on the findings, the individual filter systems can be updated to prevent further attacks by this and similar malware as quickly as possible.

One possibility for dynamic analysis is to let the malicious code perform its task in the secure environment of a sandbox. This method can be well automated to obtain certain results. The filter systems can be updated based on these results. Does the code change certain files, does it make changes in the registry or has it generally adapted the system settings to DNS servers, for example? Who does the malware contact? These and other questions can be answered in the following way.

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Various possibilities of use

The most obvious application of the data obtained from malware analysis for IT security companies is to improve their defense methods and thus better protect their customers from attacks. To do this, analysts extract certain binary patterns and use them to create so-called Yara rules with which malware samples can be found, categorized and grouped. Behavior signatures applied in the sandbox can detect and categorize certain behavior patterns of malicious code.

An example: In the sandbox, an Office document in the file attachment is opened. There the behavioral signatures recognize that the document to be examined begins to collect and send information about user accounts. If this analysis takes place in a cloud-based environment, it is then possible to intercept the conspicuous emails and thus completely block the attacks.

All of these and many other defense measures should help to intercept and prevent an attack at the earliest possible point so that the damage caused by malware is as small as possible or, better yet, does not occur at all.

Much of the raw data obtained by malware analysis and the findings derived from it are also useful for general prevention. Research projects can benefit from this and make their scientifically-sound results available to the general public. In addition, the publication of malware analyses also serves to educate the public. Increasing knowledge about the approaches of cyber attacks and malware attacks helps to limit their success rates.

EFAIL: A vulnerability in the PGP and S/MIME encryption methods?

EFAIL: A vulnerability in the PGP and S/MIME encryption methods?

UPDATE from May 16, 2018:

In order to proactively protect our corporate customers, who are still encrypting and decrypting their emails via an in-house solution and have not yet booked the Hornetsecurity Encryption Service, from EFAIL, we have also developed a special filter level for attacks according to the EFAIL pattern. The only prerequisite for this is that their email communication runs via the Hornetsecurity servers, which is generally the case with our email security products.

 

The filter level is already activated by default for all our customers who have booked at least the Hornetsecurity spam filter service and. It protects not only against EFAIL, but also against future attacks with similar patterns.

 

+++++

 

A known vulnerability is transferred to the PGP and S/MIME protocols and takes email manipulation to a new level. No problem for Hornetsecurity.

On Monday, May 14, 2018, a team of security researchers from the University of Applied Sciences Münster, the Ruhr University Bochum and the University of Leuven (Belgium) published a paper that questions the security of the PGP and S/MIME encryption standards and thus attracts worldwide attention.

However, the vulnerabilities discovered (CVE-2017-17688 and CVE-2017-17689) do not affect the protocols themselves, but use an already known vulnerability to decrypt encrypted emails by the mail client and send them to the attacker.

A prerequisite for the execution of the attacks is that the attacker already possesses emails in encrypted form. To do this, the emails need to be intercepted during transport. The attacker must have previously executed a man-in-the-middle attack (MitM) or compromised a mail server to gain access to the emails passing through him or the server. Only if these requirements are met, the attacker can execute one of the EFAIL attacks described in the paper.

The authors of the paper present two similar attacking methods to decrypt emails with existing PGP or S/MIME encryption.

The first method is quite simple, but limited to certain email clients (Apple Mail, iOS Mail, Mozilla Thunderbird) and any third-party plug-ins installed there:

To do this, the attacker creates an email with three body parts. The first part formats the email as HTML and inserts an image tag with a target website. The quotation marks and the image tag are not closed. This is followed in the second body part by the PGP- or S/MIME-encrypted text. The third part consists of HTML formatting again and closes the image tag from part one.

EFAIL vulnerabilty pgp smime encryption methods

(Source: EFAIL attacks, 14/05/04 )

If the attacker sends this email to the sender of the encrypted message, it is possible that the message is decrypted and transmitted to the stored website. To do this, the email client must be configured so that it automatically downloads external images without asking the user.

The second way to read PGP or S/MIME encrypted emails is a well-known method of how to extract plain text in blocks of encrypted messages.

The attacking scenarios are called CBC attack (S/MIME) and CFB attack (PGP). They determine a known text portion in an encrypted message and overwrites subsequent blocks with their own content. The EFAIL attack inserts an image tag with a target website into the encrypted text, as described in the first part. If the message is then delivered to the actual recipient of the encrypted message, it is possible that the message is decrypted and transmitted to the attacker.

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The emails encrypted by Hornetsecurity are protected by design against attacks of this kind, since Hornetsecurity does not even allow the different content types (multipart/mixed) required for the attack.

The encryption methods themselves – S/MIME and PGP – were not broken; rather, vulnerabilities were found in email clients for HTML emails that bypass these encryption techniques. In addition, we object to the recommendation of various security researchers to generally deactivate content encryption: PGP and S/MIME are still not per se more insecure than a pure transport-encrypted transmission or no encryption at all, even after this publication. Since the attack requires a MitM attack, i.e. a breaking of the possible transport encryption, a general levering out of content encryption would be fatal: Possible attackers could even read the email traffic directly like a postcard!

Hornetsecurity Encryption Service, which is immune to EFAIL, does not require any client plug-ins: Encryption and decryption are fully automated by Hornetsecurity in the cloud – no installation, maintenance or user interaction is required – simply secure!

Further information:

Hornetsecurity updates Advanced Email Signature and Disclaimer with new features

Hornetsecurity updates Advanced Email Signature and Disclaimer with new features

Pittsburgh, May 08, 2018 – Hornetsecurity, a German-based cloud security solutions company that recently opened its first United States base of operations in Pittsburgh, has updated its Advanced Email Signature and Disclaimer service with new features that provide significant upgrades and additional user-friendly applications.

Advanced Email Signature and Disclaimer Editor

Advanced Email Signature and Disclaimer Editor

Advanced Email Signature and Disclaimer - Hide empty fields in the editor

Advanced Email Signature and Disclaimer – Hide empty fields in the editor

Advanced Email Signature and Disclaimer Disclaimer offers an elegant solution for creating uniform company-wide content by ensuring all email signatures are attached in the same format, regardless of whether the message was sent from a PC, tablet or mobile phone.

Advanced Email Signature and Disclaimer Editor

Advanced Email Signature and Disclaimer Editor

In the original version, some fields in certain signatures would remain empty. Thanks to this upgrade, users can create additional sub-signatures within existing signatures, including slogans, logos or banners that promote upcoming trade shows or new products a company wants to highlight within a specific timeframe. Companies can activate and centrally manage the sub-signatures on a group basis, as well as use them for targeted marketing campaigns.

Advanced Email Signature and Disclaimer Mobile View

Advanced Email Signature and Disclaimer Mobile View

Advanced Email Signature and Disclaimer Mobile View (empty fields)

Advanced Email Signature and Disclaimer Mobile View (empty fields)

Advanced E-Mail Signature and Disclaimer Editor Untersignaturen

Advanced E-Mail Signature and Disclaimer Editor Untersignaturen

In addition, users can now include signatures and disclaimers not only within HTML emails, but also in plain text emails, significantly increasing the consistency and professional appearance of corporate email traffic.

Advanced E-Mail Signature and Disclaimer

Advanced E-Mail Signature and Disclaimer bei E-Mails mit Plain Text

“The signature at the end of a professional email is like a digital business card and serves as an important branding tool for every company,” Hornetsecurity CEO Oliver Dehning said. “With these newly added features, IT administrators and corporate marketing teams will have fresh opportunities to shape, sharpen and strengthen their company’s image.”

Further information to Hornetsecurity Advanced Email Signature and Disclaimer :

“For your safety” – Beware of fake ING-DiBa emails

“For your safety” – Beware of fake ING-DiBa emails

Cybercriminals are currently trying to obtain sensitive data from ING-DiBa customers with dubious fake emails. The fake email claims that a problem has occurred during a routine security check of the online banking system. It advises that customers should immediately log on to an external website to avoid troubles with their bank.

However, in reality, this is a phishing attack that tries to collect personal information. In the following blog article, you will learn in detail how to protect yourself from fake emails or phishing attacks.

The fake email from our example

Fake E-Mail

A German ING-DIBA fake email (click for zoom)

The adjacent picture shows the detailed structure of the fake email – allegedly sent by ING-DiBa – in an iPhone mailbox. In fact, the email is part of a mass phishing attack and the message was sent fraudulently to a variety of email recipients.

For example, the subject line states “For Your Safety (Reference Number: xyz)”, and the presumable arbitrary order of the combination was set to “kx5qrvnzx3h” in this case. Before we blackened the personal information for reasons of data protection, we noticed that both the recipient’s address and the sender’s address had the same information. This was already a first indication of a fake email.

This scam is not uncommon amongst perpetrators when it comes to gathering information about their randomly selected victims via phishing. Those affected are especially inclined to follow the attached link if the phishing or fake email is opened on a mobile device, as it is in this case. This is particularly true if they are actual customers of the bank mentioned in the email.

In everyday life, too, recipients of phishing emails are also quick to follow the link when receiving such an email. The attacker offers the targeted person appropriate options in case a recipient does not have an account with ING-DiBa. In our example, the recipient has the opportunity to follow a flashy red button and allegedly communicate that he is not a customer of ING-DiBa. The destination of the link, however, is a phishing website, which is intended to tap user data in a big way from the mostly unsuspecting victims. The fake security notification of ING-DiBa is not an isolated case.

6 tips to detect phishing or fake emails

With the following tips, you will be able to detect phishing or fake emails to protect yourself from being affected by such attacks.

Feature No. 1: The salutation

It is striking that either a standard phrase is used to address the target person, or the salutation is completely missing. Very rarely recipients of phishing emails are addressed with their whole name. This is due to the fact that fake emails are not isolated cases, but often automated emails which are sent out millions of times. Individual addresses are rather the exception. In our example there was no address at all.

Once the victim has entered his details into the according form fields and pressed the confirmation button, the cybercriminal is in possession of the login details. Now he can make orders in online shops under false names or get access to sensitive account or company data. The phishing attack has been successful.

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Feature No. 2: Content of the email

A phishing mail is contextually designed to hide the true intentions towards the recipient at least until he first clicks on one of the attached links. These following baits are very popular with cyber crooks:

  • Fake emails in the form of alleged PayPal security notifications
  • Phishing emails which seem to come from banks or other institutions
  • Fake email notifications that seem to come from Amazon or Ebay
  • Fake security issues in social media accounts that need to be resolved promptly

This shows that cybercriminals are very creative when it comes to fooling their victims.

Feature No. 3: The call to action

Once the attacker has created and sent out his fake email, he urges the recipient to act. In this specific case, the targeted person is initially led to an external page by clicking on a link. This page usually resembles closely the login area of a bank, an online retailer or any other company that offers certain Internet services.

Feature No. 4: The time shortage

An effective means often used by attackers is the limitation of time. This is an attempt to put the victim under stress and distract it. In our example, this is stated as follows: “Please log into your account as soon as possible to avoid any delay in your banking activities.”

Fear-spreading phrases in the subject line, such as “Your account has been suspended” or “An amount has been debited from your account” are also quite popular and common. These sentences cause some recipients to panic, so they follow the attached link without much thought.

Feature No. 5: Questionable buttons and links

In order to successfully carry out the process of phishing, a related link in text or button form is part of the standard repertoire of any phishing or fake email. This is also the case in our example.

Therefore, when it comes to questionable security queries that have a link, we recommend that you do not access these links from your email program. Instead, you should always directly log in to your user accounts via a browser or via the official website of the provider. This applies to online services of any kind.

Feature No. 6: This is how reputable companies and institutes work

As far as the detection of phishing emails or fake emails is concerned, it should always be remembered that reputable companies or institutes would never ask you to disclose personal information via email.

For this reason, various banks regularly point to the problem of fake emails or the so-called phishing mails. One bank states for example:

“Volksbank Raiffeisenbank or BVR will never ask bank customers for personal information such as PIN or account number via email. Neither will we insert a link to online banking in emails or ask bank customers to make test or remittance transfers. These practices are always indicators of attempted fraud.” (Source: Volksbank Raiffeisenbank)

Therefore, you can delete such an email immediately. This is ultimately the simplest way to counter a phishing attack.

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