Operators Used Four Different DLL Side-Loading Scenarios To Install And Execute New Malware After Removing A Resident PlugX Backdoor. Targets And Tools Suggest Adversaries Are A Chinese APT Group

OXFORD, U.K.  — novembre 4, 2020 —

Sophos, a global leader in next-generation cybersecurity, has uncovered attackers using DLL side-loading to execute malicious code and install backdoors in the networks of targeted organizations. A report published today, “A New APT uses DLL Side-loads to Killl Someone,” outlines the discovery of four different DLL side-loading scenarios, which all share the same program database path and some of which carry a file named “KilllSomeOne.” The targeting of these attacks—against non-governmental organizations and other organizations in Myanmar—and other characteristics of the malware suggest that the attackers involved may be a Chinese APT group.

The attackers have implemented a spin on the side-loading methods often associated with Chinese threat actors and used in the well known PlugX backdoor. Two of the scenarios deliver a payload carrying a simple shell, while the other two carry a more complex set of malware that can install and execute the payload and collect data on the target. Combinations from both sets were used in the same attacks.

The malware also looks for a running process name starting with AAM, probably because earlier PlugX side-loading scenarios used the file name “AAM Updates.exe.” If the malware finds this file, it kills and deletes it. This suggests the KilllSomeOne backdoor was designed to remove earlier PlugX infections, either because the original attackers wanted to push out new code or because the attacks were implemented by a different group leveraging existing infrastructure.

The KilllSomeOne malware code includes several strings of plain text. The samples Sophos analyzed were written in poor English and with clear political messages. According to Sophos, it is unusual to find these types of political messages in what appears to be a nation-state threat, and it could mean less professional cybercriminals are involved or the attackers inserted the messages to misdirect security researchers.

“This is an intriguing new discovery and a good reminder that the operators behind advanced targeted attacks rarely are a homogeneous pool or even see themselves as a single entity. Individual contributors come with very different skill sets and capabilities. Some of them are highly adept, while others are little more than your average cybercriminal,” said Gabor Szappanos, threat research director, Sophos. “The group responsible for the ‘KilllSomeOne’ attacks doesn’t fall clearly at either end of the spectrum. For instance, the perpetrators opted for fairly simple implementations in coding—especially in encrypting the payload—and the messages hidden in their samples are what you’d expect from script kiddies. On the other hand, the targeting and deployment is that of a serious APT group. It’s not clear from our analysis whether this group will eventually return to more traditional implants like PlugX or keep going with its own code.”

Further information on KilllSomeOne can be found on SophosLabs Uncut where Sophos experts regularly publish their latest research and breakthrough findings. Threat researchers and IT managers can follow SophosLabs Uncut in real time on Twitter at @SophosLabs.

Human-led threat hunting and response help to identify and mitigate new and unknown threats. At Sophos,  these experts are available through Sophos Managed Threat Response and Sophos Rapid Response services.

À propos de Sophos

Sophos est un leader mondial et un innovateur dans le domaine des solutions de cybersécurité avancées, qui comprend des services managés de détection et réponse (MDR) et de réponse aux incidents, ainsi qu’un vaste portefeuille de technologies de sécurité qui protègent les systèmes endpoint, les réseaux, les messageries et le Cloud contre les cyberattaques. Sophos est l’un des plus grands fournisseurs de cybersécurité et protège aujourd’hui plus de 500 000 entreprises et plus de 100 millions d’utilisateurs dans le monde contre les adversaires actifs, les ransomwares, le phishing, les malwares, etc. Les services et produits de Sophos sont connectés à travers sa console d’administration Sophos Central basée dans le Cloud et sont alimentés par Sophos X-Ops, l’unité de renseignement sur les menaces transversale de la société. L’intelligence de Sophos X-Ops optimise l’ensemble de l’écosystème de cybersécurité adaptatif (ACE) de Sophos, qui comprend un datalake centralisé exploitant un ensemble riche d’API ouvertes à destination des clients, des partenaires, des développeurs et des autres fournisseurs de cybersécurité et de technologies de l’information. Sophos fournit des services de cybersécurité aux entreprises qui ont besoin de solutions de sécurité clés en main et entièrement gérées. Les clients peuvent également gérer leur cybersécurité directement avec la plateforme d’opérations de sécurité de Sophos ou utiliser une approche hybride en complétant leurs équipes internes avec les services de Sophos, notamment la chasse aux menaces et la remédiation. Sophos vend ses produits par l’intermédiaire d’un réseau mondial de partenaires et de fournisseurs de services gérés (MSP : Managed Service Provider). Le siège de l’entreprise est basé à Oxford, au Royaume-Uni. Plus d’informations sont disponibles sur www.sophos.fr.