New research indicates cybercriminals are making attacker attribution increasingly complex by re-using tools and tactics from other hacker groups.

Researchers on the Kaspersky Lab Global Research and Analysis Team (GReAT) found evidence that sophisticated threat actors are hacking other attack groups to steal victim data, borrow tools and techniques, repurpose exploits, and compromise the same infrastructure.

The result is a major attribution challenge. Reliable threat intelligence is based on identifying patterns and tools associated with a specific threat actor. These signs help security researchers map the targets and behaviors of different attackers. When hackers start hacking one another, using the same tools, and targeting the same victims, the model breaks down.

Kaspersky believes these types of attacks are most likely to be used among nation-state backed groups targeting foreign or less competent actors. IT security researchers should know how to detect and interpret these attacks so they can present their intelligence in context.

The idea behind this research was to better understand the practice of fourth-party collection through signal intelligence (SIGINT), which involves the interception of a foreign intelligence service's computer network exploitation (CNE) activity. Researchers observed attackers' actions and in doing so, found evidence showing they actively steal from one another.

"In less technical terms, fourth-party collection is the practice of spying on a spy spying on someone else," explain GReAT researchers Juan Andrés Guerrero-Saade and Costin Raiu in a post on Kaspersky's SecureList blog.

There are two main approaches to these attacks: passive and active. Passive involves intercepting other groups' data while it's in transit between victims and command-and-control (C&C) servers. It's almost impossible to detect. Active collection, however, leaves footprints.

Active attacks involve breaking into another threat actor's malicious infrastructure. It's dangerous for attackers because it heightens the risk of detection, but it's also beneficial. The success of active collection depends on the target making operational security errors.

During their investigation of specific threat actors, the GReAT team found several pieces of evidence suggesting these active attacks are already happening in the wild. These include:

Backdoors installed in another actors' C&C infrastructure

Researchers found two examples of backdoors in hacked networks, which let attackers persistently infiltrate another group's operations. One of these instances was discovered in 2013 during an investigation of the NetTraveler attacks. Researchers obtained a server and, during their analysis, discovered a backdoor seemingly placed by another actor. It's believed the goal was to maintain prolonged access to the NetTraveler infrastructure or the stolen data.

Another was found in 2014 while investigating a hacked website used by Crouching Yeti, also known as "Energetic Bear," an APT actor active since 2010. Researchers noticed the panel managing the C&C network was modified with a tag pointing to a remote IP in China, which is believed to be a false flag. They think this was also a backdoor belonging to another group.

Sharing compromised websites

In 2016, Kaspersky found a website hacked by DarkHotel also hosted exploit scripts for another attacker. The second, which was codenamed "ScarCruft," primarily targeted Russian, Chinese, and South Korean organizations. The actor relied on watering hole and spearphishing attacks.

Targeting attackers' focus areas

By infiltrating a group with stake in a specific region or industry, attackers can benefit from another group's work and specifically target certain groups of people. It's risky for attackers to share victims in the case one group gets caught; if they do, analysis will reveal who the other threat actors were.

In November 2014, Kaspersky researchers located a server in a Middle East research institution hosted implants for advanced actors Regin, Equation Group, Turla, ItaDuke, Animal Farm, and Careto. The discovery of this server marked the beginning of the eventual discovery of the Equation Group.

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