StrelaStealer Phishing Attacks: A Deep Dive into the Tactics and Techniques

Strelastealer Phishing Attacks

A recent revelation by cybersecurity researchers sheds light on a new wave of phishing attacks targeting over 100 organizations across the E.U. and the U.S., launched by a sophisticated information stealer known as StrelaStealer. Let’s delve into the specifics of these attacks to gain deeper insights into their modus operandi.

Phishing Simulation

The Phishing Lure

The campaigns are initiated through spam emails with attachments that serve as the delivery mechanism for the StrelaStealer’s malicious payload. To evade detection, attackers constantly alter the file format of the email attachments, making it challenging for traditional signature-based detection systems to catch them.

First detected in November 2022, StrelaStealer is equipped to steal email credentials from well-known email clients and sync them to the hacker’s servers.

Since then, two large-scale campaigns involving the malware have been detected in November 2023 and January 2024 targeting tech, finance, legal, manufacturing, governmental, energy, insurance, and construction sectors in the E.U. and the U.S.

Execution of the Attack

Upon opening the malicious attachment, a JavaScript file is dropped, which subsequently triggers a batch file responsible for executing the StrelaStealer payload using a legitimate Windows component, rundll32.exe. This method of execution adds a layer of legitimacy to the attack, making it harder to detect.

Evasion Tactics

StrelaStealer employs a variety of obfuscation techniques to thwart analysis, particularly in sandboxed environments. By constantly updating both the email attachment and the DLL payload with each new wave of campaigns, threat actors stay ahead of security measures, prolonging their ability to operate undetected.

Evolution of Payload Delivery

Notably, the phishing campaigns have undergone a shift in payload delivery, transitioning from ISO files to ZIP attachments disguised as invoice-themed emails. This adaptability demonstrates the agility of threat actors in altering their tactics to maximize success rates.

Implications and Countermeasures

The emergence of StrelaStealer phishing attacks underscores the need for organizations to bolster their defenses against evolving threats. Implementing robust email security measures, educating employees about phishing awareness, and deploying advanced threat detection solutions are crucial steps in mitigating the risks posed by such attacks.


As cybercriminals continue to innovate and refine their tactics, it is imperative for cybersecurity professionals and organizations to remain vigilant and proactive in safeguarding their assets and sensitive information. By understanding the intricacies of phishing attacks like StrelaStealer, we can better equip ourselves to combat emerging threats and protect against potential breaches.

In the face of escalating cyber threats, staying informed and proactive is our best defense against malicious actors seeking to exploit vulnerabilities for nefarious purposes.

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