Summary Points
- Attackers embed unique identifiers and tracking tokens within URL userinfo fields to bypass traditional URL reputation filters and monitor campaign effectiveness.
- Use of hostname labels starting or ending with hyphens exploits parser inconsistencies, avoiding detection by strict validators and sandboxing solutions.
- Incorporating the victim’s email address in the URL path can mislead parsers, enabling phishing links to evade automated filtering and URL analysis.
Threat, Attack Techniques, and Targets
The threat involves sophisticated phishing emails using a single URL that employs three tricks to deceive detection tools. The attackers craft URLs with multiple features to confuse security controls. First, they include a userinfo field with a random string before the “@” symbol. This makes each link unique, defeating blacklists and reputation checks. Second, the hostname contains a hyphenated subdomain like “gynd–.koncar-hr.com,” which may bypass strict URL validators. Lastly, the victim’s email address appears in the URL path. This helps phishing kits pre-fill login forms and makes the link appear more personalized. The URL looks like a normal email link but actually carries hidden malicious intent. The main targets are users who may click on these links, often those who trust email sources or are unaware of complex URL tricks.
Impact, Security Implications, and Remediation Guidance
This technique can lead to successful phishing attacks. Because these URLs bypass some security filters, victims may unknowingly visit malicious pages and reveal sensitive information. The tricks used can evade detection because different parsers interpret the URL parts differently. For example, some tools ignore the userinfo or reject hyphenated hostnames, while browsers follow the URL standard correctly. This means a naive filter might miss these links, while a user could be compromised. As a result, organizations should keep their URL validation and filtering systems updated. They should also train staff to recognize suspicious URLs with multiple “@” symbols, hyphens in hostnames, or email addresses in paths. If needed, remediation guidance should be obtained from cybersecurity vendors or authority sources familiar with these URL tricks, as specific strategies are not included in this report.
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