Microsoft Windows Defender Research discovered an attack campaign that utilized spear phishing emails impersonating U.S. Department of State employees to gain remote access to victims’ machines.

Investigators said the majority of those targeted in the campaign, which began in mid-November, were public-sector institutions and non-governmental organizations based in the U.S. The spear phishing emails purported to be notifications from Microsoft’s cloud-based storage system, OneDrive, that indicated a State Department employee had a file they wanted to share.

Those who fell for the bait unleashed an obfuscated PowerShell command and a dynamic-link library (DLL) payload that gave threat actors the ability to control victims’ devices from a command-and-control (C&C) server.

What Happens When Threat Actors Use CobaltStrike

While threat actors often spend considerable time developing their own malicious software code, investigators said those behind this particular attack campaign also made use of CobaltStrike, a commercially available tool that is normally used for penetration testing.

If attackers gained access to a victim’s machine, they could use CobaltStrike to download and install additional software, capture what users input into their systems, execute arbitrary commands through Windows Management Instrumentation (WMI) or PowerShell, and escalate privileges.

While third-party analysts attributed the attacks to a group known as APT29, or CozyBear, which coincides with a group Microsoft calls YTTRIUM, Microsoft does not yet believe that enough evidence exists to attribute this campaign to YTTRIUM.

The Best Way to Shield Against Spear Phishing

As with similar spear phishing attacks, this campaign shows how adept cybercriminals have become in using what look like legitimate names and subject matter in their messages to compel a response — in this case, what looked like an important communication from the Department of State.

In a recent SecurityIntelligence podcast, IBM X-Force Red senior security consultant Chris Sethi described the need for an internal awareness program about adhering to IT security best practices, such as not clicking on potentially malicious links and attachments. The safest organizations take this one step further by having a third party conduct routine tests to ensure employees are putting the right behaviors into practice.

Source: Microsoft Windows Defender Research