Growth and Commoditization of Remote Access Trojans Veronica Valeros Sebastian Garcia Department of Computer Science Department of Computer Science Czech Technical University Czech Technical University Prague, Czech Republic Prague, Czech Republic [email protected] [email protected] Abstract—In the last three decades there have been significant remains to today, their use has evolved. In the last decade changes in the cybercrime world in terms of organization, type more and more RATs were used in espionage, financial of attacks, and tools. Remote Access Trojans (RAT) are an and state sponsored attacks [3]–[5]. While many of them intrinsic part of traditional cybercriminal activities but they had their source code leaked or open sourced, the market have become a standard tool in advanced espionage and scams for Fully Undetectable (FUD) RATs and special plugins attacks. The overly specialized research in our community matured. Nowadays, RATs have become a commodity. on Remote Access Trojans has resulted in a seemingly lack Despite the abundance of reports on individual RAT of general perspective and understanding on how RATs have families and attacks that use them [6], there is no previous evolved as a phenomenon. This work presents a new generalist research that looks at RATs as a whole. The growth and perspective on Remote Access Trojans, an analysis of their evolution of RATs appears to have escaped public attention growth in the last 30 years, and a discussion on how they so far. The lack of a more generalist research hinders have become a commodity in the last decade. We found that the understanding and development of new techniques and the amount of RATs increased drastically in the last ten years methods to better detect them. and that nowadays they have become standardized commodity This paper aims to start a discussion on RATs as a products that are no very different from each other. unique phenomenon that requires further study. We argue that in the last 10 years a shift has occurred in the threat Index Terms—remote access trojans, underground economy, landscape where RATs have become a commodity. This cybercrime, marketplaces, malware, commoditization work analyzes the growth of Remote Access Trojans, de- scribes their key technological elements, their functionality, 1. Introduction and analyzes how they propagate. Furthermore, this work presents a timeline of the last 30 years of RATs evolution, Remote access software is a type of computer program a detailed overview of the most well-known RATs during that allows an individual to have full remote control of 2019-2020, and an analysis of how they have been commer- the device where the software is installed. Remote Access cialized. Tool refers to a type of remote access software used for The main question this research explores is, are Remote benign purposes, such as TeamViewer [1] or Ammyy Ad- Access Trojans a commodity in the underground? Answer- min [2], which are common tools used by billions of users ing this question, the contributions of this paper are: worldwide. Remote Access Trojans (RAT) are a special type of remote access software commonly used for malicious • The first and most comprehensive timeline of the purposes, where (i) the installation is done without user last 30 years of RATs. consent, (ii) the remote control is done secretly, and (iii) • An overview of the commoditization of the most the program hides itself in the system to avoid detection. well-known RATs in 2019-2020. The distinction between tools and trojans was created by • A first analysis on the types of attacks and attackers the information security industry to distinguish benign from using RATs. malicious RATs, however in the underground, attackers claim all RATs are Remote Access Tools. 2. Methodology Early Remote Access Trojans were used for pranks and for fun, to showcase skills, and to brag in hacking forums. To address the analysis of RATs we first searched and Developing your own RAT was an entry level skill that inex- methodologically analyzed a comprehensive list of Remote perienced users were somehow expected to rapidly acquire. Access Trojans since their first public appearance in 1996 Websites like megasecurity.org were used to list and publish until 2018. These RATs, shown in the timeline of Figure1, new RATs, many of which were never developed further. were found from public sources and inquiries with the While the challenge of building highly functional RATs community, and are the base tools analyzed in this work. The years 2019 and 2020 were not included in this research it. Upon execution the key will be used to automatically as the information available for this time is at the moment decrypt the original program. Crypters are used to avoid not comprehensive and incomplete. detection by anti-virus engines. We chose a small subset of RATs in order to study their specific characteristics, their users and how they are com- 3.2. Thirty Years Timeline of RATs mercialized. These RATs were selected using the following methodology. First, we searched on well-known forums for To better understand the growth and evolution of RATs, RATs that users were talking about or recommending to each it was necessary to investigate and build a corpus of the most other in the period from January 2019 to March 2020. We well-known Remote Access Trojans in history that had the consulted HackForums [7], Sinister.ly [8], and Nulled [9]. key technical elements described previously. We were able Second, taking as an input the list of RATs created in the to find, reference and document many RATs since 1996 to previous step, we searched for those RATs in websites that 2018 by looking at reports, code, and forums. These RATs were selling hacking tools, software, and other goods. Third, were also grouped in families, with slight variations of the we limited the scope of RATs to those that were being sold same RATs grouped together. The final list contains 337 in two or more of the above mentioned marketplaces. Fourth, unique families of RATs, registering the first time seen, or we assembled the final list of RATs to study: WebMonitor date of the first public report about them. RAT, Android Voyager RAT, Remcos RAT, SpyNote RAT, The collected information was used to build the first and Luminosity Link RAT, Omni Android RAT, Ozone RAT, most comprehensive timeline of RATs to date. The timeline Imminent Monitor RAT, NanoCore RAT, NetWire RAT and is illustrated in Figure1, and it is divided in three phases CyberGate RAT. Fifth, further information was collected shown in the figure as different dotted lines. The first phase from public intelligence sources such as blogs, news articles is from 1990 to 1999; the second phase is from 2000 to and forums on each of the selected RAT. 2009; and the third phase is from 2010 to 2018. In Figure1 we also highlight in bold pink color the 11 RATs that will 3. Overview of Remote Access Trojans be analyzed in more detail in the following sections. The oldest RAT was first developed in 1996 [10], how- In order to define a common ground to further the ever legitimate Remote Access Tools were first created in understanding of RATs, we first introduce some of the key 1989 [11]. Since then, the number of RATs has grown technical elements of every Remote Access Trojan. Then rapidly. Figure1 illustrates 337 of the most well-known RAT we present a timeline showing the growth of RATs over families during 1996–2018. The first period, 1996-1999, the last 30 years. Finally we discuss common functionality was marked by home-made RATs. In these years, everyone found among RATs. made their own RAT, however these did not prosper nor were heavily used. Among the most prominent ones were 3.1. Key Technical Elements Back Orifice, Sub7 and Netbus, which together defined a generation by being innovative and disruptive. The second Remote Access Trojans have two key elements: client period, 2000-2009, showed a slight growth of more mature and server. Additional RATs components include the RATs, that were intended for fun but were started to be used builder, plugins and crypter. A RAT server is the program for attacks and profit. Among the highlights of this period installed on the victim’s device. The server is configured to are Gh0st, PoisonIvy and DarkComet. The third period, connect back to the attacker. The client is the program used 2010-2018, showed an important shift. RATs became a by the attacker to monitor and control infected victims: it commodity. The market matured, RAT sellers were expected allows the visualization of all active victims infections, dis- to provide support, new features, and in some cases even to plays general information about each infection, and allows host part of the infrastructure. to manually perform individual actions on each victim. The growth of RATs in the last decade depends on The builder is a program that allows to create new a combination of multiple factors. The maturity of the RAT servers with different configurations. When attackers cybercrime ecosystem, the specialization of work in the move infrastructure quickly, launch new attacks, and require underground communities, and interdependence of threat flexibility, builders save time and provide agility. actors are some of the key factors that led to an increase RATs come with certain fixed functionality. To add more in the demand of new and better malicious software, and capabilities, some RATs rely on plugins. Not all RATs offer RATs among them. To understand the real cause however, this capability, however the most used ones do, and good a more extended analysis and study is needed. plugins are craved by the cybercrime community.