Old dog, new tricks – Analysing new RTF-based campaign distributing Agent Tesla, Loki with PyREbox

This blog post was authored by Edmund Brumaghin and Holger Unterbrink with contributions from Emmanuel Tacheau.

Executive Summary

Cisco Talos has discovered a new malware campaign that drops the sophisticated information-stealing trojan called “Agent Tesla,” and other malware such as the Loki information stealer. Initially, Talos’ telemetry systems detected a highly suspicious document that wasn’t picked up by common antivirus solutions. However, Threat Grid, Cisco’s unified malware analysis and threat intelligence platform, identified the unknown file as malware. The adversaries behind this malware use a well-known exploit chain, but modified it in such a way so that antivirus solutions don’t detect it. In this post, we will outline the steps the adversaries took to remain undetected, and why it’s important to use more sophisticated software to track these kinds of attacks. If undetected, Agent Tesla has the ability to steal user’s login information from a number of important pieces of software, such as Google Chrome, Mozilla Firefox, Microsoft Outlook and many others. It can also be used to capture screenshots, record webcams, and allow attackers to install additional malware on infected systems.

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