Email Salting Attacks: How Hidden Text Bypasses Security
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Last Updated: 8 min read
Email salting is like a smuggler hiding contraband in plain sight, which would definitely pass by your eyes, with you being none the wiser.
According to a report by Cisco Talos, email salting attacks have become a growing concern, enabling phishing campaigns to even impersonate brands like Wells Fargo and Norton LifeLock, all the while evading detection mechanisms.
Read this guide about how email salting takes place, its impact on your email security, and how tools like PowerDMARC act as an X-ray scanner for your inbox, making these almost invisible threats visible to you.
Key Takeaways
- For IT leaders and security teams in regulated industries, understanding and mitigating advanced email threats like salting is necessary for compliance and brand protection.
- Email Salting attacks are email threats where cybercriminals insert hidden text within emails to bypass spam filters.
- Threat actors can deploy several techniques to facilitate these attacks, including Hidden Text Salting, Bayesian Poisoning, Email Header Salting, etc.
- Email Salting can assist in the evasion of detection and delivery of phishing emails, ransomware, business email compromise, and social engineering attacks.
- PowerDMARC’s unified platform provides advanced threat intelligence and real-time alerts to detect and prevent these sophisticated attacks across multi-domain organizations.
What is an Email Salting Attack?
In an email salting attack, threat actors insert hidden text within an email to try to bypass your spam filters and email security systems. However, the concept of salting is not malicious in itself. Traditional salting randomizes passwords and is quite an effective way to enhance password security. Email salting attack techniques differentiate themselves from safe salting methods by manipulating email content in deceptive ways for ulterior motives.
Attackers use Email Salting techniques to:
- Evade spam detection by inserting invisible characters.
- Disrupt email analysis tools that rely on word patterns.
- Increase their chances of reaching your inbox rather than spam.
Common Methods Used in Email Salting Attacks
1. Hidden Text Salting
In this technique, attackers insert hidden or obfuscated text into emails. These invisible messages can be:
- Hidden Unicode characters (zero-width characters) can be inserted within words to bypass keyword-based filters.
- CSS properties can be easily manipulated to hide malicious texts. These might be harmless commands like display:none or font-size:0, but they can be dangerous when executed.
- If you choose to write with font colour white on a white background, it would be undecipherable and invisible to the naked human eye. This is a simple yet often overlooked way to hide dangerous code or text.
2. Bayesian Poisoning
In this email salting attack technique, random or benign words are inserted into malicious emails to bypass Bayesian spam filters. Bayesian filters use probability calculations to find a difference between spam and legitimate messages. Attackers aim to manipulate and bypass these filters by adding random or often well-thought-out words that fail to get flagged as spammy. This enables the Bayesian filters to trust that the email content is safe, letting it pass through.
3. Email Header Salting
Attackers insert redundant or misleading information in an email’s Reply-to or Return-path fields to modify email headers. This results in malicious emails evading detection and making them appear more legitimate than they really are.
4. Unicode Homoglyph Attacks
Attackers can easily replace email content with characters that may appear similar to the naked eye, but are not the same! A common example would be replacing “m” with “rn” which can sometimes work in evading spam detection filters.
How to Recognize Email Salting Attack Indicators
Identifying email salting attacks requires you to pay attention to subtle signs and anomalies. Manual detection techniques rely on this heavily. These are some of the key indicators to watch out for:
Common Signs of Email Salting Attacks
- Suspicious formatting: Unusual spacing, inconsistent fonts, or text that appears cut off
- Hidden characters: Copy-paste text that includes extra characters not visible in the email
- Unexpected HTML/CSS: Emails with complex HTML structures for simple messages
- Odd sender behaviors: Legitimate-looking senders with unusual email patterns
- Content inconsistencies: Messages that don’t match the sender’s typical communication style
Detection Checklist for IT Teams
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Detection Tools for Email Salting Attacks
An organization with multiple channels of communication that host sensitive information cannot rely on simple do-as-it-comes monitoring. You will need specialized tools and techniques to detect email salting. This becomes more important against sophisticated attacks. Take a look at this comprehensive overview of solutions available to you:
Industry-Standard Detection Tools
| Tool Type | Features | Best For |
|---|---|---|
| Email Security Gateways | Advanced content analysis, hidden text detection | Enterprise environments |
| Advanced Spam Filters | Machine learning, pattern recognition | SMB and enterprise |
| Forensic Analysis Tools | Deep email inspection, source code analysis | Security teams, investigators |
| PowerDMARC Platform | Predictive threat intelligence, real-time alerts | Multi-domain organizations, MSPs |
Real-World Examples of Email Salting Attacks
To give you a better picture of how it looks in reality, we have two real-world case studies of businesses that suffered email salting attacks. This can help you better prepare your own defenses. Here are the anonymized examples based on recent incidents:
Case Study 1: Financial Services Impersonation
Attack Flow: Attackers impersonated a major bank using hidden text salting to bypass email filters. They inserted invisible Unicode characters between letters in words like “bank” and “account”, successfully evading keyword detection.
Impact: More than 10,000 recipients received the malicious emails, with a 15% click-through rate before detection.
Detection Method: Advanced content analysis tools identified the hidden characters during post-event investigation.
Case Study 2: Software License Scam
Attack Flow: Cybercriminals used CSS properties to hide random text within genuine-looking software renewal notices, successfully bypassing Bayesian filters.
Impact: Targeted IT administrators at 500+ organizations, resulting in credential theft and unauthorized software purchases.
Lessons Learned: Organization implemented visual content analysis tools later to detect hidden CSS elements.
Implications for Email Security
Email Salting attacks pose a huge risk to your email security and domain reputation. They can have several negative effects like:
- Phishing: Email Salting can facilitate phishing attacks, increasing the success rate of malicious code reaching victims’ systems.
- Ransomware: By allowing fraudulent messages to slip through, Email Salting attacks can lead to the spread of ransomware!
- Social engineering: Email Salting can also facilitate social engineering tactics, making employees more vulnerable to fraud.
Organizational Impact and Business Consequences
Going beyond the immediate security risks, there are broader business implications that you need to cater to:
- Compliance Risks: Data protection failure can violate regulatory requirements in finance, healthcare, and similar regulated industries
- Brand Reputation: Successful attacks lower brand image, trust, and credibility
- Financial Consequences: Data breaches resulting from salting attacks lead to significant financial losses and legal liability
- Operational Disruption: Incident response and recovery efforts disrupt normal business operations in a large capacity, slowing down workflow for months
How to Prevent Email Salting Attacks
As attackers grow their arsenal, tech stacks to counter them have also shown up. These are some innovative ways you can stop email salting attacks:
1. Advanced Filtering
Developing more advanced filtering mechanisms can prove to be a game-changer when it comes to email salting exploits. These would be capable of detecting hidden texts and unusual HTML structures. Security teams can come up with more sophisticated mechanisms or software for text parsing that can help mitigate salting attacks.
2. AI and Machine Learning
With advancements in AI, the future looks hopeful when it comes to mitigating email salting threats. AI-driven tools can help identify trends effectively. A good example is PowerDMARC’s Predictive Threat Intelligence analysis. It proactively monitors and predicts advanced attack patterns, giving security teams an edge.
3. Visual Content Analysis
Many email security tools benefit from incorporating visual content analysis to detect concealed messages within emails. As cybercriminals insert hidden texts to facilitate email salting attacks, visual analysis is a great way to detect these invisible anomalies.
Layered Defense StrategiesA multi-layered approach to email security is the most proven and effective method against cyber threats like email salting. Make sure to include:
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How PowerDMARC Helps Prevent Email Salting Attacks
PowerDMARC’s email security platform is designed to protect you from powerful email salting attacks. Its features include:
- Predictive analytics to identify emerging attack trends before they become widespread
- Real-time alerts for suspicious email authentication patterns and potential threats
- Centralized dashboard for real-time visibility across all domains and email sources
- Advanced threat intelligence to detect and block hidden-text exploits before they reach inboxes
- Role-based access and domain grouping for large teams and MSPs managing multiple client environments
- 24/7 global support and compliance-ready reporting for regulated industries
Why Choose PowerDMARC for Email Salting Protection:
- Unified platform managing DMARC, SPF, DKIM, BIMI, MTA-STS, and TLS-RPT
- Available on AWS and Azure marketplaces for seamless enterprise deployment
- SOC2 and ISO27001 certified platform trusted by organizations worldwide
- Dedicated support for enterprises and MSPs with complex multi-domain requirements
What to Do If You Suspect an Email Salting Attack
If you believe your organization has been targeted by email salting, it is best to be quick and follow these steps:
Immediate Response Actions
- Do not interact with the suspicious email; avoid clicking any links or downloading attachments
- Report immediately to your IT security team or email administrator
- Preserve evidence by forwarding the email to your security team without modifying it
- Check email source code for hidden elements or suspicious HTML/CSS
- Alert colleagues who may have received similar emails
Organizational Response Steps
- Isolate affected systems if any users interacted with the malicious email
- Review security protocols and update email filtering rules
- Conduct forensic analysis to understand the attack methodology
- Update incident response procedures based on lessons learned
- Consider implementing advanced email security solutions like PowerDMARC
Summing Up
With PowerDMARC, organizations can future-proof their email security against evolving threats like email salting, ensuring compliance and peace of mind. By future-proofing your domain names, you can protect your brand from the next big data breach or cyber exploit.
You can get started today. Implement DMARC, SPF, and DKIM on your domain to safeguard your emails against impersonation. These authentication protocols are the stepping stone to security against a wide range of email-based cyber attacks.
Ready to see how PowerDMARC can protect your organization from advanced threats like email salting? Start your 15-day trial today.
Frequently Asked Questions
Why does email salting work?
Email salting works because of how traditional spam filters work. They rely on pattern recognition and keyword detection, which can be easily bypassed. By inserting hidden text or characters, attackers can break up recognizable spam patterns while keeping the malicious content intact for recipients. It essentially exploits the gap between how machines and humans process text.
Can I be hacked if I reply to an email?
Simply replying to an email typically won’t hack your system, but it is still advised against. It confirms to attackers that your email address is active, making you a bigger target to subsequent attacks. Always verify the sender’s identity before responding to suspicious emails.
How do I stop hundreds of spam emails daily?
To reduce spam volume: 1) Implement robust email authentication (DMARC, SPF, DKIM), 2) Use advanced spam filtering solutions, 3) Never reply to spam emails, 4) Avoid sharing your email publicly, 5) Use separate emails for different purposes, and 6) Consider professional email security solutions like PowerDMARC for comprehensive protection.
What makes PowerDMARC different from other email security tools?
PowerDMARC offers a unified platform that combines email authentication, advanced threat intelligence, and predictive analytics in one solution. Unlike other services, PowerDMARC provides centralized management for multiple domains, role-based access for teams, and 24/7 global support, making it ideal for enterprises and MSPs managing complex email environments.
Domain & Email Security Expert at PowerDMARC
Yunes is an Operations Team Lead at PowerDMARC with expert knowledge in email authentication and security. Yunes is a Microsoft-certified Azure Administrator Associate with certifications in CompTIA A+ and many more.
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