Sophisticated covert cyberattack campaign targets military contractors

A cyberattack campaign, potentially bent on cyber espionage, is highlighting the increasingly sophisticated nature of cyberthreats targeting defense contractors in the US and elsewhere.

The covert campaign, which researchers at Securonix detected and are tracking as STEEP#MAVERICK, has hit multiple weapons contractors in Europe in recent months, including potentially a supplier to the US F-35 Lightning II fighter aircraft program.

What makes the campaign noteworthy according to the security vendor is the overall attention the attacker has paid to operations security (OpSec) and to ensuring their malware is hard to detect, difficult to remove, and challenging to analyze.

The PowerShell-based malware stager used in the attacks have “featured an array of interesting tactics, persistence methodology, counter-forensics and layers upon layers of obfuscation to hide its code,” Securonix said in a report this week.

Uncommon Malware Capabilities

The STEEP#MAVERICK campaign appears to have launched in late summer with attacks on two high-profile defense contractors in Europe. Like many campaigns, the attack chain began with a spear-phishing email that contained a compressed (.zip) fie with a shortcut (.lnk) file to a PDF document purportedly describing company benefits. Securonix described the phishing email as being similar to one it had encountered in a campaign earlier this year involving North Korea’s APT37 (aka Konni) threat group.

When the .lnk file is executed, it triggers what Securonix described as a “rather large and robust chain of stagers,” each written in PowerShell and featuring as many as eight obfuscation layers. The malware also features extensive anti-forensic and counter-debugging capabilities which include monitoring a long list of processes that could be uses to look for malicious behavior. The malware is designed to disable logging and bypass Windows Defender. It uses several techniques to persist on a system, including by embedding itself in the system registry, by embedding itself as a scheduled task and by creating a startup shortcut on the system.

A spokesperson with Securonix’s Threat Research Team says the number and variety of anti-analysis and anti-monitoring checks the malware has is unusual. So, too, is the large number of obfuscation layers for payloads and the malware’s attempts to substitute or generate new custom command-and-control (C2) stager payloads in response to analysis attempts: “Some obfuscation techniques, such as using PowerShell get-alias to perform [the invoke-expression cmdlet] are very rarely seen.”

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