Pierluigi Paganini October 10, 2019

New espionage malware found targeting Russian-speaking users in Eastern Europe

ESET found an advanced malware piece of malware named Attor, targeting diplomats and high-profile Russian-speaking users in Eastern Europe.

ESET researchers discovered an advanced malware piece of malware named Attor, that was used in cyberespionage operations on diplomats and high-profile Russian-speaking users in Eastern Europe.

Threat actors have been using Attor since 2013, the malicious code remained under the radar until last year.

The researchers believe that the threat actor behind Attor a state-sponsored group involved in highly targeted attacks on selected targets.

“Attor’s espionage operation is highly targeted – we were able to trace Attor’s operation back to at least 2013, yet, we only identified a few dozen victims.” reads the analysis published by ESET.

“For example, in order to be able to report on the victim’s activities, Attor monitors active processes to take screenshots of selected applications. Only certain applications are targeted – those with specific substrings in the process name or window title.”

The researchers believe that the malware was specifically developed to infect mainly Russian-speaking users, it targets popular Russian apps and services, including the social networks Odnoklassniki, and VKontakt, VoIP provider Multifon, IM apps Qip and Infium, search engine Rambler, email clients Yandex and Mail.ru, and payment system WebMoney.

The malware implements a modular structure with a dispatcher and loadable plugins, all of which are implemented as dynamic-link libraries (DLLs). The attackers first compromise the target dropping the components on disk, then loads the dispatcher DLL.

The Attor malware makes sophisticated use of encryption to hide its components.

The plugins are delivered as DLLs asymmetrically encrypted with RSA, then they are recovered in memory, using the public RSA key embedded in the dispatcher.

“In total, the infrastructure for C&C communication spans four Attor components – the dispatcher providing encryption functions, and three plugins implementing the FTP protocol, the Tor functionality and the actual network communication.” continues the analysis. “This mechanism makes it impossible to analyze Attor’s network communication unless all pieces of the puzzle have been collected. “

“We were able to recover eight of Attor’s plugins, some in multiple versions – we list them in Table 2. Assuming the numbering of plugins is continuous, and that actors behind Attor may use different sets of plugins on a per‑victim basis, we suspect there are even more plugins that have not yet been discovered. ” continues the analysis.

The analysis of the samples of the malware revealed the presence of an interesting module designed to detect when users connected modems and older phones to their devices. The malware is able to collect info about the files present on connected devices.

“The most curious plugin in Attor’s arsenal collects information about both connected modem/phone devices and connected storage drives, and about files present on these drives. It is responsible for collection of metadata, not the files themselves, so we consider it a plugin used for device fingerprinting, and hence likely used as a base for further data theft.” reads the report.

“While Attor’s functionality of fingerprinting storage drives is rather standard, its fingerprinting of GSM devices is unique.”

Attor’s device monitoring module implements a unique fingerprinting feature of GSM devices. Whenever a modem or a phone device is connected to a COM port, Device monitor uses AT commands to communicate with it.

ESET believes that the authors of the Attor malware developed this module to target users owning older mobile handsets, or even a custom GSM-capable platform.

“A more likely explanation of the plugin’s main motive is that it targets modems and older phones. Alternatively, it may be used to communicate with some specific devices (used by the victim or target organization) that are connected to the COM port or to the USB port using a USB-to-serial adaptor.” concludes the analysis. “In this scenario, it is possible the attackers have learned about the victim’s use of these devices using some other reconnaissance techniques.”

Pierluigi Paganini

(SecurityAffairs – Attor, malware)

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