Attackers launched a new campaign that leveraged updated downloaders and a backdoor to distribute samples of the Zebrocy malware family.

On August 20, researchers at ESET spotted a new Zebrocy campaign in which the Sednit group targeted embassies of and ministries of foreign affairs in Eastern European and Central Asian countries. The campaign started with a phishing email that contained a malicious attachment. Once opened, this otherwise blank document downloaded a remote template hosted on Dropbox to execute malicious macros and ultimately load the malware.

ESET came across a few surprises along the way. For instance, researchers found that the Sednit group had rewritten its Delphi downloader in Golang for its latest campaign. This downloader had fewer data-gathering capabilities than the group’s previous downloaders. In addition, researchers observed that the backdoor was now written in Golang and no longer in Delphi.

The Slovakian security firm reasoned that Sednit made these changes to help the campaign’s components more effectively evade detection.

A Look at Zebrocy’s History

The Sednit group has been around since at least 2004, making it one of the more longstanding cyberthreats. ESET had a chance to examine the Zebrocy malware in depth in November 2018, when the security firm found several indicators suggesting that a team less experienced than the Sednit core was responsible for developing the threat and its components. Even so, the malware continued to evolve.

In December 2018, for instance, Palo Alto Networks found a new Go variant of the attack tool. In June 2019, Kaspersky Lab observed Zebrocy using a new downloader to target organizations in Germany, the U.K., Iran, Ukraine and Afghanistan.

How to Defend Against Phishing-Borne Threats

Security professionals can help defend their organizations against phishing-borne threats like Zebrocy by using multifactor authentication (MFA) and identity and access management (IAM) to remedy the weaknesses of password-only authentication for work accounts. Companies should also advocate for phishing simulations that can evaluate their organization’s defenses against an email attack campaign.