Microsoft has been observing the activities of a cyber espionage group that has leveraged a Windows patching system in attacks aimed at organizations in South and Southeast Asia.
The APT actor, dubbed by Microsoft “Platinum,” has been active since at least 2009, primarily targeting victims via spear phishing attacks. Its activities have mainly focused on government organizations, intelligence agencies, defense institutes and ISPs, and the information stolen by the group has been used for indirect economic advantages, not for direct financial gain.
Microsoft’s Windows Defender Advanced Threat Hunting team discovered that the group has been using a feature called hotpatching to hide some of its malicious tools from security products.
Hotpatching is a feature first shipped by Microsoft with Windows Server 2003 to allow the installation of updates without having to reboot or restart a process. The feature was removed in Windows 8.
Researchers warned in 2013 that hotpatching, which requires administrator permissions, can be abused for malicious purposes, but Microsoft says this is the first time the technique has been observed in the wild.
Hotpatching allows attackers to inject malicious code into processes without being detected by security products, which in many cases monitor non-system processes for other, more common types of injection methods. In the case of the Platinum group, the hotpatch API has been used to inject a backdoor into the svchost process.
“We first observed a sample employing the hotpatching technique on a machine in Malaysia. This allowed PLATINUM to gain persistent access to the networks of companies it targeted and victimized over a long period without being detected,” Microsoft said in a blog post.
Researchers have identified several other techniques that contributed to Platinum’s activities going undetected for several years. First of all, the group conducts a small number of campaigns each year and it puts a significant effort into covering its tracks by deleting malicious components and allowing components that are hosted on a remote server to load only once.
The threat actor has leveraged custom-built malware that it often updates in an effort to evade detection. The backdoors used by the attackers are configured to operate only during normal work hours in an attempt to disguise malicious activities within regular traffic.
Platinum has also leveraged several zero-day exploits in its attacks, which indicates that the group has considerable financial resources.
“Any of these traits by themselves could be the work of a single resourceful attacker or a small group of like-minded individuals, but the presence of all of them is a clear indication of a well-resourced, focused, and disciplined group of attackers vying for information from government-related entities,” Microsoft said in a report detailing the activities and techniques of the Platinum group.
Related: Malicious Document Builder Used in East Asia APT Attacks
