In today’s rapidly evolving cybersecurity landscape, phishing attacks remain one of the most persistent threats to individuals and organizations alike. As these schemes grow more sophisticated, a particular variant known as Barrel Phishing (or double-barrel phishing) has emerged, posing a serious challenge to even the most cautious email users. Understanding this tactic—which blends deception, timing, and psychological manipulation—is essential to defending against it.
TLDR:
Barrel phishing attacks use a tactical two-step approach—first sending a benign email to create a false sense of trust, followed by a malicious email soon after. The attacker’s goal is to lull victims into lowering their guard. Recognizing the pattern and educating users is key to preventing such attacks. Organizations must combine technology and awareness training to effectively defend against this increasingly common threat.
What Is Barrel Phishing?
Unlike traditional phishing that often delivers a malicious payload immediately, barrel phishing opts for subtlety. It is a technique where cybercriminals first initiate contact with a non-threatening, friendly, or generic message. This is known as the benign bait.
After a short interval—sometimes minutes, hours, or even days—the attacker sends a second message within the same thread or email context. This second email contains the malicious payload, such as a link to a phishing site or a malicious attachment. The attacker leverages the previous message to create a false sense of legitimacy and continuity.
These attacks often take on the appearance of conversations between co-workers, clients, or vendors. The attackers may use public information like LinkedIn profiles or company websites to craft convincing scenarios.
Why Is Barrel Phishing So Effective?
This method thrives on the principle of psychological priming. By first sending an innocuous message, the attacker establishes a “trust baseline” with the target. When the follow-up arrives, the recipient assumes it’s from the same trustworthy source and is less likely to question the legitimacy of the email.
Some of the psychological tactics employed include:
- Familiarity: Using existing email threads to make messages appear genuine.
- Urgency: Pressing for quick action in the second email to prevent overthinking.
- Authority: Impersonating executives, managers, or IT support to pressure compliance.
Furthermore, email security filters often fail to detect barrel phishing because the first message doesn’t contain any harmful links or attachments. By the time the second email arrives, it’s already within an established email thread, which may cause automated systems and even human readers to overlook red flags.
Common Characteristics of a Barrel Phishing Attack
Barrel phishing attacks can differ in execution but often share several defining features:
- Step 1: The Bait – An initial message that appears normal and benign. Examples include a quick greeting (“Hi, are you free for a quick chat?”) or a request for general information.
- Step 2: The Hook – A follow-up message sent in the same thread, typically urging immediate action. This may include:
- A link to a fraudulent login page
- A malicious document attachment
- A request for sensitive information such as account credentials, tax information, or wire transfers
- Contextual Relevance – Targeted messages often reference the recipient’s job title, department, or current projects to add credibility.
Real-Life Examples
In a well-known 2023 incident, a major financial services firm fell prey to a barrel phishing campaign. An employee received a light, friendly email from an attacker posing as another department head. A day later, the same thread continued with a message asking the employee to review an “updated finance report” attached in a PDF format, which was actually ransomware.
Another case involved an executive assistant receiving an email from a spoofed account resembling the CEO. The initial message asked if the assistant had a moment, and the follow-up requested they purchase gift cards for a client meeting.
How to Detect a Barrel Phishing Attempt
Detection often depends on user vigilance and well-configured systems. Here are signs to look for:
- Unusual Timing: Is there a sudden follow-up email after an unusually long gap?
- Mismatch in Tone or Grammar: Does the tone of the second email match the first? Are there signs of rushed or non-native language use?
- Email Address Spoofing: Is the sender address subtly different from a legitimate domain? (e.g., “@micros0ft.com” instead of “@microsoft.com”)
- Unexpected Requests: Are you being asked to click on an unexpected link, download an attachment, or transfer sensitive information?
How to Prevent Barrel Phishing Attacks
Preventing barrel phishing requires both technical barriers and behavioral awareness. Here’s how businesses and individuals can better protect themselves:
1. Employee Training and Awareness
- Educate employees about the two-step nature of these attacks.
- Instill a culture of skepticism for unexpected or urgent email requests—even if part of an existing thread.
- Implement regular phishing simulations to keep awareness high.
2. Email Filtering and Security Tools
- Use advanced email filtering solutions that utilize AI to detect unusual patterns in email behavior.
- Implement Domain-based Message Authentication, Reporting & Conformance (DMARC) protocols to prevent email spoofing.
- Employ attachment sandboxing: open suspicious documents in isolated environments to test for malware.
3. Multi-Factor Authentication (MFA)
- MFA adds an extra layer of security. Even if login credentials are stolen via phishing, access remains protected.
4. Secure Email Gateways and Threat Intelligence
- Leverage threat intelligence feeds that update your email filters with known phishing patterns and domains.
- Set up rules to flag all messages from external senders, especially those resembling internal staff.
5. Verification Protocols
- Encourage employees to verify unusual requests via another channel—like calling the sender or speaking in person—before acting.
What To Do If You Receive or Fall for a Barrel Phishing Email
If you suspect a barrel phishing attempt or realize you’ve interacted with one, act immediately:
- Do not respond or click further.
- Notify your IT or security team and forward the email for analysis.
- Run antivirus software or endpoint protection scans to check for malware.
- Reset passwords on any potentially compromised accounts.
- Monitor for signs of identity theft or unauthorized access.
Conclusion
Barrel phishing attacks are a vivid example of how cybercriminals continue to evolve their strategies to stay one step ahead of the average user and traditional security systems. The use of a two-phased communication style makes these attacks more believable and therefore more dangerous.
However, with the right combination of user education, technical safeguards, and security protocols, organizations can dramatically reduce their risk. Staying alert, questioning even familiar interactions, and maintaining strong cyber hygiene are more important than ever as phishing threats continue to evolve.
Every email decision can be critical. When in doubt, verify before you click.