URL Schema Obfuscation: A Growing Malware Distribution Technique


In the constantly evolving landscape of cybersecurity threats, attackers are continuously looking for novel ways to get around security measures and exploit vulnerabilities. One such method that has been gaining popularity is URL Schema Obfuscation.

URL Schema Obfuscation includes misusing the URL schema to obfuscate a URL’s end destination. This blog post covers notions of URL Schema Obfuscation, its consequences in cybersecurity, and the necessity for efficient detection and prevention.

Understanding URL Schema and Obfuscation

The addresses used to find information on the internet are called URLs (Uniform Resource Locators). They adhere to a particular format that is described in RFC1738. For instance, the format for an HTTP URL is “http://host:port/path?searchpart“. The portion of the URL schema, such as “http://“ or “https://,” defines the protocol or scheme used to access the resource.

In order to fool victim’s and avoid discovery, URL Schema Obfuscation leverages the URL schema’s structure and constituent parts. One of the techniques often employed involves inserting an “@” sign in the URL, specifically in the username section.

Obfuscating the destination server using the “@” Sign
Inserting a “@” symbol in the URL, notably in the username area, is one method used in URL Schema Obfuscation. The username section is indicated in the URL format before the “@” sign, but browsers normally ignore it. Attackers benefit from this behaviour by changing the username component of the URL to the target email domain, which makes the URL look more legitimate, particularly for spear-phishing campaigns.

An authentic URL might resemble- “http://username:password@example.com/path/file“, where “example.com” designates the server’s location. The attacker would substitute the email domain for the username section in an obfuscated URL, creating “http://example.com/path/file“. Due to this alteration, the URL appears to be a genuine one, which increases the likelihood that victims may fall for the phishing scam.


URL Schema Obfuscation presents substantial difficulties for network defenders and security technology. Attackers can circumvent security mechanisms that rely on knowing which server a URL points to by exploiting the URL structure, potentially resulting in gaps in visibility and coverage. When traditional URL parsing logic encounters these encoded URLs, visibility into threat campaigns and actor infrastructure is lost.

Furthermore, the method boosts the success of phishing attempts (and more specifically, spear-phishing attempts) because victims are more likely to trust URLs that look like legitimate domains. Attackers might increase the success rate of their campaigns by exploiting URL Schema Obfuscation, jeopardising the security of individuals and organisations alike.

Detection and Prevention

Schema for Addressing URLs Obfuscation necessitates proactive network defence measures. They should look for “@” indications in URLs’ username sections and scrutinise URLs that lack an appropriate username-password combination. It is also critical to have URL parsing methods that can handle alternate hostname forms and recognise non-standard IP address representations.

To properly detect and prevent obfuscated URLs, security solutions such as web gateways, email filters, and endpoint protection systems should be equipped with extensive URL analysis capabilities. Furthermore, user education and awareness programmes are critical in reducing the risks connected with URL-based assaults.


URL Schema Obfuscation is a developing malware delivery technique that uses the URL schema to conceal a URL’s true destination. Attackers mislead victims, avoid detection, and boost the success rate of their attacks by putting “@” marks in the username field. Understanding the complexities of URL Schema Obfuscation is critical for network defenders in order to design effective detection and prevention measures to protect persons and organisations from developing cyber threats. We can collectively reinforce our defences against URL-based attacks and reduce their influence on the cybersecurity landscape by remaining vigilant and implementing proper security measures.


  1. Don’t @ Me: URL Obfuscation Through Schema Abuse | Mandiant.