Yellow Liderc: The Evolving Cyber Threat from Iran


Published on Oct 26, 2023   —   3 min read


In the world of cybersecurity, the only constant is change. But some things, like the ingenuity of hackers, remain eerily consistent.

Staying ahead of emerging threats is a Sisyphean task. Today, we delve into the evolving tactics, techniques, and procedures (TTPs) of Yellow Liderc, an Iran-based threat actor that has been active since 2018. This group has shown a particular focus on sectors like Aviation, Automotive, Aerospace, and more. So, buckle up as we take you through a labyrinth of malware, strategic web compromises, and phishing activities that would make even James Bond raise an eyebrow.

Who is Yellow Liderc?

Yellow Liderc is an Islamic Revolutionary Guard Corp (IRGC) aligned threat actor. Their geographic focus spans from the Middle East to Europe and the Americas. They employ a mix of custom and off-the-shelf malware, including PowerShell backdoors and infostealers. Their modus operandi involves phishing, social engineering, and strategic web compromises.

The Evolution of Tactics

Since 2022, Yellow Liderc has been compromising legitimate websites, inserting malicious JavaScript to fingerprint website visitors. This tactic, often referred to as a "watering hole attack," has been particularly focused on the maritime, shipping, and logistics sectors within the Mediterranean.

IMAPLoader: The New Kid on the Block

In the ever-evolving landscape of cybersecurity, staying one step ahead of threat actors is akin to a game of high-stakes chess. Yellow Liderc, not one to rest on its laurels, has upped its game with a new malware sample—IMAPLoader.

What Makes IMAPLoader Unique?

IMAPLoader is a DLL written in .NET, and it serves as a downloader. While that might sound like standard fare in the world of malware, what sets this piece of code apart is its innovative use of email for command and control (C2) communication. But wait, there's more. IMAPLoader employs a new injection technique known as 'AppDomain Manager Injection.'

Breaking Down 'AppDomain Manager Injection'

This injection technique was first publicly disclosed in 2020 and has been relatively under the radar. It forces a Microsoft .NET application to load a specially crafted .NET assembly—in this case, IMAPLoader. This is a significant departure from Yellow Liderc's previous modus operandi, indicating not just an evolution but perhaps a revolution in their toolkit.

Indicators of Compromise (IoCs)

For the tech-savvy among you, here's a list of SHA-256, SHA-1, and MD5 indicators to watch out for.

The Phishing Pond

Yellow Liderc's phishing operations are multifaceted, targeting both broad and niche sectors. They frequently use domains mimicking Microsoft's login pages to capture credentials, capitalizing on the widespread use of Microsoft accounts. Additionally, the group has a keen focus on Europe's travel and hospitality sectors, deploying tailored phishing campaigns that mimic well-known agencies and chains to capture sensitive information like payment details. These phishing attempts often serve as the initial stage in multi-layered attacks, enabling deeper intrusions into organizational networks.

Given the complexity of Yellow Liderc's tactics, organizations must adopt a multi-faceted defense strategy. This should encompass regular staff training on phishing recognition, the implementation of multi-factor authentication, and continuous network monitoring. Understanding the nuances of Yellow Liderc's phishing strategies allows organizations to better prepare for and defend against these evolving threats.

The Final Hop's Take

The emergence of IMAPLoader as part of Yellow Liderc's toolkit signifies a notable evolution in the group's capabilities. This new addition underscores the necessity for organizations to continually reassess and update their cybersecurity strategies. In an environment where threat actors are constantly innovating, maintaining a static defense posture is insufficient. Organizations should consider incorporating advanced threat detection mechanisms and staying abreast of the latest threat intelligence to effectively mitigate risks posed by evolving threat actors like Yellow Liderc.

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