SMTP Explanation

SMTP, or Simple Mail Transfer Protocol, is the standard protocol used for sending emails across the Internet. It operates on a client-server model, where the sender’s email client communicates with the email server to transmit the message to the recipient’s email server, which then delivers it to the recipient’s inbox.

SMTP is a text-based protocol and operates over TCP/IP, typically using port 25. While SMTP is robust and has been the backbone of email communication for decades, it was not originally designed with security in mind. Over time, enhancements like SMTP over SSL/TLS have been introduced to secure email transmission, but the protocol’s openness still leaves it vulnerable to various attacks.

Suggested: SSL/TLS monitoring explained in details

What is SMTP Smuggling?

SMTP Smuggling is a sophisticated attack technique that exploits the way email servers handle SMTP traffic. Specifically, it targets the discrepancies in how different email servers and security gateways interpret SMTP commands and email headers.

In essence, SMTP Smuggling involves crafting email messages that appear legitimate to some servers but are interpreted differently by others, enabling attackers to bypass security filters, deliver malicious content, or even exfiltrate data. This attack vector can be particularly dangerous because it can evade traditional security mechanisms designed to inspect and filter email traffic.

Key Components 

• Header Injection and Manipulation: SMTP Smuggling often involves injecting additional SMTP headers or manipulating existing ones to deceive downstream email servers. For example, an attacker might craft an email with two “Content-Length” headers, each with a different value. Some servers might use the first header, while others might use the second, leading to different interpretations of where the email body starts and ends.
• Multi-Stage Parsing Differences: Different email servers and security appliances may parse SMTP traffic differently. Attackers exploit these parsing discrepancies to create situations where one server interprets a part of the message as legitimate while another interprets it as malicious. For example, an email could be crafted to appear benign to a security gateway but malicious to the final mail server.
• Boundary Mismatch Attacks: These involve crafting email messages that confuse the boundary definitions between headers and the body, or between different parts of a MIME (Multipurpose Internet Mail Extensions) email. This mismatch can cause email security solutions to misinterpret the boundaries, allowing malicious content to slip through.

How does SMTP Smuggling work?

SMTP Smuggling typically follows these steps:

1. Crafting the Email: The attacker crafts an email with specific SMTP headers and commands that exploit the differences in how email servers and security gateways interpret SMTP traffic. This may involve splitting the email into parts that are handled differently by each server in the relay chain.
2. Sending the Email: The malicious email is sent through a series of relay servers. The attacker’s goal is to have the email appear benign to the initial security gateway but to have its true malicious nature revealed once it reaches a later point in the relay chain.
3. Exploiting Inconsistencies: As the email traverses through different servers, some may interpret the crafted commands differently. For example, one server might treat a part of the email as a legitimate command, while another might ignore it, allowing the attacker to introduce malicious content or bypass security controls.
4. Bypassing Security: The email eventually reaches the target server or inbox, where its malicious payload can be executed. Because the attack exploited inconsistencies in server interpretations, traditional security measures may have been bypassed, leaving the target vulnerable.

Detection and Mitigation Strategies

Given the covert nature of SMTP smuggling, detecting it can be challenging. However, there are steps that organizations can take to mitigate the risk:

• Use Advanced Email Security Solutions: Implement advanced email security solutions that go beyond traditional spam filters. These solutions should include deep content inspection, behavioral analysis, and machine learning to detect and block sophisticated threats like SMTP smuggling.
• Regularly Update and Patch Email Servers: Ensure that your email servers and associated software are regularly updated and patched. Many SMTP smuggling attacks exploit vulnerabilities in outdated software, so keeping your systems current is critical.
• Monitor Email Traffic: Implement monitoring tools to analyze email traffic patterns. Anomalies in SMTP communication, such as unusual command sequences or unexpected payloads, can be indicators of smuggling attempts.

Suggested: What is SMTP Monitoring?

• Educate Users: Train employees to recognize phishing attempts and other suspicious emails. While SMTP smuggling can bypass technical defences, a vigilant and well-informed workforce can serve as a strong line of defence.
• Implement DMARC, SPF, and DKIM: Domain-based Message Authentication, Reporting, and Conformance (DMARC), Sender Policy Framework (SPF), and DomainKeys Identified Mail (DKIM) are protocols that help authenticate email senders. Properly configuring these protocols can reduce the risk of email spoofing and smuggling.
• Perform Regular Security Audits: Conduct regular security audits of your email infrastructure to identify potential vulnerabilities and weaknesses. This proactive approach can help you address issues before they are exploited by attackers.

Conclusion

SMTP smuggling is a sophisticated and potentially devastating attack vector that targets the core of email communication. As cybercriminals continue to evolve their tactics, it is crucial for organizations to stay ahead of the curve by implementing robust email security measures and educating their employees about the dangers of these attacks. By understanding how SMTP smuggling works and taking proactive steps to protect your email systems, you can significantly reduce the risk of falling victim to this hidden threat.

The post What is SMTP Smuggling? How to detect and prevent it? appeared first on ClouDNS Blog.

DMARC explained

DMARC is an authentication, policy and also reporting protocol. It uses both SPF and DKIM and adds linkage to the “From” domain name, policies for handling the incoming email in case of failure and something very important – report for the sender. That way the sender can see if there is a problem, and act on it.

The main purpose of DMARC is to protect against direct domain spoofing. If an attacker tries to send email from not authorized, DMARC will detect it and block it.

Combined with BIMI, you will also give proper protection to your brand reputation by providing authentic messages.

Why SPF and DKIM are not enough?

SPF – Sender Policy Framework has the goal to validate the senders’ servers. The receivers check the SPF record and see the IP address. It should be matching the IP address of the domain of the sender.

A problem with the SPF is that the SPF record applies to the return path of the domains, not to the domain, that shows in the “From” on the user interface. DMARC fixes this flaw with alignment, a match, between the visible “From” and the server authenticated by SPF.

DKIM – DomainKeys Identified Mail. The owner can use DKIM record to sign the emails that it sends. The emails will have extra data (encrypted) in the header that can be verified through the DNS. This technology is not flawless too. Many companies don’t rotate the key, and that can be a big problem. This is another thing, DMARC fixes. It provides rotating keys.

How does DMARC work?

We mention already that DMARC uses policies. The administrator sets them, defining the email authentication practices and what should the receiving email server do if an email violates a policy.

When the receiving email server gets a new email, it makes a DNS lookup to check the DMARC record. It will look for:

• If the DKIM signature is valid.
• The IP address of the sender, if is one of the allowed by him (SPF record).
• If the header shows proper “domain alignment”.

With all of the above in consideration, the server DMARC policy to accept, reject or flag the email.

In the end, the server will send a message to the sender with a report.

Benefits of DMARC

Here are some of the main advantages of implementing this advanced protocol.

For the sender:

• Shows that the email uses authentication – SPF and DKIM.
• Receives a feedback about the sent email.
• Policy for failed email.

For the receiver:

• Provide authentication for the incoming emails
• Evaluating the SPF and DKIM
• See what the sender prefer – policy
• Returns feedback to the sender

DMARC Record example

DMARC records are a simple text (TXT) DNS records. They look like this:

“v=DMARC1;p=reject;pct=100;rua=mailto:postmaster@dmarcdomain.com”

• V – the version of the protocol. In the example is version 1
• Pct – % of the messages that are subject to filtering (pct=20)
• Ruf – URI for forensic reports (ruf=mailto:authfail@example.com)
• Rua – URI for aggregate reporting (rua=mailto:aggrep@example.com)
• P – Policy, organizational domain (p=quarantine)
• Sp – Policy, subdomains of the organizational domain (sp=reject)
• Adkim – Alignment for DKIM (adkim=s)
• Aspf – Alignment for SPF (aspf=r)

DMARC record generator by ClouDNS

Why use DMARC?

DMARC is a protocol used to help prevent email fraud and phishing attacks. Here’s why it’s important and why you should use it:

• Prevention of Email Spoofing: It helps prevent attackers from spoofing your domain, a common tactic in phishing attacks. By authenticating emails sent from your domain, DMARC ensures that only authorized senders can use your domain name.
• Improved Email Deliverability: Implementing it can help improve your email deliverability by reducing the chances of your legitimate emails being flagged as spam or being rejected by email servers. When email receivers see that your domain is protected by DMARC, they are more likely to deliver your emails to the inbox.
• Protection of Brand Reputation: Phishing attacks that use your domain can harm your organization’s reputation and trustworthiness. DMARC helps protect your brand reputation by preventing unauthorized use of your domain in phishing emails, thereby maintaining trust with your customers and partners.
• Visibility and Control: DMARC provides visibility into email traffic sent from your domain through reporting mechanisms. You can monitor email authentication results and receive reports on email activity, including information about legitimate and fraudulent email senders. This allows you to take proactive measures to protect your domain and email infrastructure.

What is an MX record?

Conclusion

DMARC can significantly lower the number of fraud emails and spam. It is not 100% bulletproof, but it adds a lot of extra protection in comparison with the other two solutions – SPF and DKIM. The reporting functionality is welcome plus too.

The post DMARC, the solution for your phishing problems appeared first on ClouDNS Blog.

What is a Phishing attack?

A phishing attack is a malicious attempt by cybercriminals to deceive individuals into providing sensitive information through fraudulent emails, messages, or websites. The attackers disguise themselves as trustworthy entities, such as banks, social media platforms, or government agencies, to gain victims’ trust and exploit their vulnerability for personal gain.

How does it work? Step by step

Here’s how a typical phishing attack unfolds:

1. Bait Creation: The first step in a phishing attack involves creating an enticing bait, such as an urgent request to update account information, a tempting offer, or a warning about a compromised account.
2. Delivery: The bait is then delivered through various means, such as email, SMS, social media messages, or even malicious ads.
3. Deception: The message typically contains a sense of urgency or fear, compelling the recipient to take immediate action without questioning its legitimacy.
4. Linking to fake websites: Phishing emails often include links to fake websites that closely resemble legitimate ones. These fake sites are designed to collect the victim’s login credentials and personal information when entered.
5. Data collection: Once the victim enters their information, the cybercriminals capture it and can use it for identity theft, financial fraud, or other malicious purposes.

Types of phishing attacks

There are several variations of phishing attacks, including:

• Email phishing: The most common type, where fraudulent emails are sent to deceive recipients into revealing sensitive information.
• Spear phishing: Highly targeted attacks aimed at specific individuals or organizations, often using personalized information to appear more convincing.
• Whaling attacks: Similar to spear phishing but focused on high-profile individuals or executives within an organization.
• Clone phishing: Attackers create a replica of a legitimate email and modify it to include malicious content or links.
• Pharming: Redirects victims to fraudulent websites even if they enter the correct web address.

How do spear phishing attacks differ from standard phishing attacks?

Standard phishing attacks cast a wide net, sending mass emails or messages impersonating well-known entities to deceive as many victims as possible. These attacks use generic content and fake websites to trick recipients into revealing personal information.

In contrast, spear phishing attacks are highly targeted and personalized. Cybercriminals gather specific details about their victims, crafting convincing messages that appear to come from trusted sources like colleagues or business partners. This tailored approach increases the likelihood of success, as victims are more likely to fall for the authenticity of the communication, leading to the disclosure of sensitive data or malware installation.

2023 Phishing attack Statistics

According to a staggering statistic from IT Governance, an estimated 3.4 billion malevolent emails, mainly in the form of phishing, hit our inboxes every single day, marking it as the predominant form of cybercrime (IT Governance, 2023). The objective? To ensnare unsuspecting individuals into revealing their login credentials. IBM’s Cost of a Data Breach Report further sheds light on this issue by revealing that stolen credentials, indeed, represent the primary cause of data breaches, accounting for 19% of all cyber attacks (IT Governance, 2023).

The threat intensifies when we shift our gaze towards corporate security. A report by Digital Guardian has identified that a staggering 90% of corporate security breaches can be traced back to phishing attacks (IT Governance, 2023). The toll on organizations is heavy. Each piece of personal information pilfered via a phishing attack, according to Venari Security, translates to an approximate loss of $181. (IT Governance, 2023).

Source: 51 Must Know Phishing Statistics for 2023, IT Governance

Source: Most Affected Industries by Phishing, Statista

In the ever-evolving landscape of phishing attacks, certain industries tend to be more targeted than others. Statista, a leading provider of market and consumer data, provides an illuminating infographic that delineates the sectors most affected by phishing.

Leading the pack, unsurprisingly, is the financial industry with 23% of phishing attempts directed towards it. This is due to the sensitive and valuable information that this sector holds, making it an attractive target for cybercriminals.

Next up, the Software-as-a-Service (SaaS) and webmail industries face their fair share of threats with 17% of the phishing attacks aimed at them. This might be attributed to the fact that many SaaS companies hold vast amounts of data on behalf of their clients, making them a rich source for phishing attempts.

What is IaaS, PaaS, and SaaS?

Social media platforms are the third most targeted, suffering from 11% of these malicious attempts. The extensive personal and business data that users tend to share on these platforms make them a fertile ground for cybercriminals.

Logistics and shipping sectors, along with e-commerce and retail, each receive 6% and 4% of the phishing attempts respectively. The payment sector is also targeted by 4% of phishing attacks. These industries, dealing with sensitive transactional data, are enticing for hackers who want to exploit the financial and personal information.

The telecom sector, with a share of 3%, and the burgeoning cryptocurrency industry, receiving 2% of phishing attempts, round out the list. It is worth noting that as the popularity of cryptocurrencies continues to grow, they may become an even more lucrative target for phishing in the future.

Impacts of Phishing Attacks

The consequences of falling victim to a phishing attack can be severe and extensive. For individuals, the theft of personal information can lead to identity theft, financial loss, and damage to personal reputation. In the context of organizations, phishing attacks can result in data breaches, financial fraud, disruption of operations, and loss of customer trust.

Beyond immediate financial and reputational harm, phishing attacks can also be used to launch more advanced cyber threats, such as ransomware, malware infections, and business email compromise (BEC) scams. By compromising the credentials of unsuspecting users, attackers gain access to organizations, enabling them to launch more sophisticated and targeted attacks.

Moreover, the indirect costs associated with phishing attacks, including incident response, remediation efforts, and regulatory fines, can be significant burdens on organizations of all sizes. The reputational damage from a successful phishing attack can ruin an organization’s brand and lose customer trust, potentially leading to long-term business consequences.

How to protect against Phishing Attack?

There are several proactive steps you can take to protect yourself against phishing attacks:

• Anti-phishing software: This type of software can identify phishing content and alert users about potential threats.
• Two-Factor Authentication (2FA): This adds an extra layer of security by requiring two types of identification before granting access.
• Monitoring service: With Monitoring service you can keep an eye on your personal data online and alert you if they detect unusual activity.
• DNS records: You can implement SPF, DMARC, DKIM, and PTR records. These email authentication methods help protect against email spoofing and increase email security.
• rDNS: Reverse DNS lookup can verify whether the server is associated with the domain it claims to represent.
• HTTPS and SSL certificates: Look for ‘https‘ in the URL and the padlock symbol in the browser for an SSL certificate that can help to identify secure websites. Phishing websites often lack these security measures, providing users with visual cues of a potential threat. 
• Education and awareness: Regular training on phishing attack recognition and safe online habits can be crucial for both businesses and individuals.
• Regular software updates: Keeping your software and systems updated ensures you have the latest security patches, making it harder for attackers to exploit vulnerabilities.

Famous Phishing Attacks

Here are some of the most popular examples of Phishing attacks:

• Target Corporation (2013)

In late 2013, Target, one of the largest retail chains in the United States, fell victim to a sophisticated phishing attack that led to massive consequences. The attack began with a phishing email sent to an HVAC vendor that had access to Target’s network. The attackers then used the compromised vendor credentials to gain entry into Target’s systems. Ultimately, the breach resulted in the theft of over 40 million credit card numbers and personal information of 70 million customers. The incident highlighted the potential cascading impact of phishing attacks on large organizations.

• Sony Pictures (2014)

In 2014, Sony Pictures Entertainment became the target of a highly publicized cyber attack. While the attack included elements beyond phishing, it was initiated through a carefully prepared email. The attackers sent phishing emails to Sony employees, tricking them into revealing login credentials. Afterwards, the attackers unleashed malware that disabled Sony’s computer systems, leading to the exposure of sensitive internal documents, emails, and unreleased films. The incident highlighted the potential for phishing to be a precursor to more extensive and damaging cyber intrusions.

• Facebook and Google (2017)

In 2017, a Lithuanian hacker produced a phishing attack targeting tech giants Facebook and Google. The attacker posed as a legitimate vendor and successfully convinced employees at both companies to wire over $100 million in payments for supposed goods and services. The scam involved fake invoices and email correspondence that appeared to be from reputable suppliers. The incident highlighted the vulnerabilities in the supply chain and payment processes of large corporations, emphasizing the need for strict verification procedures.

Conclusion

The landscape of cybercrime, particularly phishing, is ever-evolving. Therefore, staying informed and proactive in adopting protective measures is crucial. With the knowledge of how phishing works, what the current trends are, and how to defend against these attacks, individuals and organizations can greatly enhance their cybersecurity stance.

The post Understanding Phishing Attack and How to Stay Protected appeared first on ClouDNS Blog.