Remote access tool

Ryan Mazerik
April 24, 2014 by
Ryan Mazerik

Remote Access Tool is a piece of software used to remotely access or control a computer. This tool can be used legitimately by system administrators for accessing the client computers. Remote Access tools, when used for malicious purposes, are known as a Remote Access Trojan (RAT). They can be used by a malicious user to control the system without the knowledge of the victim. Most of the popular RATs are capable of performing key logging, screen and camera capture, file access, code execution, registry management, password sniffing etc.

RAT can also be called as a synonym for backdoor, which includes a client and server program. The server or the stub program, if installed in the compromised system unknowingly by the owner of that system, then it is called as a Remote Access Trojan.

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Remote Administration Trojans (RATs) are malicious pieces of software and infect the victim's machine to gain administrative access. They are often included in pirated software through patches, as a form of cracked game or E-mail attachments. After the infection, it may perform unauthorized operations and hide their presence in the infected system. An attacker can remotely control the system by gaining the key logs, webcam feeds, audio footage, screen captures, etc.

RATs normally obfuscate their presence by changing the name, size, and often their behavior or encryption methods. By doing this they evade from AV, firewalls, IDS, IPS and security defense systems. Excluding the remote access capabilities, some RATs also behave as a backdoor to the system by infecting it with viruses, worms, spyware, adware, etc. Thus, the infected machines can also be used as a bot or zombie to carry out a chain of attacks to other machines including DDOS.

RAT Detection

RATs can be avoided by verifying each piece of software before installation by using authorized program signatures. This programs signature may be available from the vendors of the products; however, it may become difficult to correlate this procedure in an organizational level. In addition, the RATs are using varied level of obfuscation methods to hide their characteristics from detection system. RAT normally injects to legitimate pieces of software or even distributed as patches or other updates, which make them difficult to be captured.

Various host and network based detection methodologies can be correlated to the proper detection of the RATs. In host-based detection, the unique characteristics of the RAT can be stores in a database level that contains the file name, size, checksum and other unique characteristics. This RAT database can be scanned with the new programs and if matching patterns are found, then can be recognized as RAT. The startup files, registries, auto start and configuration scripts can be monitored and if any distinguished behavior is detected can be detected as a RAT.

In network based detection method, the network communication protocols can be monitored to check whether if any deviation is there in the behavior of network usage. Ports can be monitored for exceptional behavior, and can analyze protocol headers of packet among the systems. The network traffic can be analyzed and the RAT behavior patterns can distinguished among other legitimate traffic.

Types of RAT

  • Back Orifice

Back Orifice 2000 (BO2K) was released in July 1999 at DefCon VII, a computer hacker convention held in Las Vegas, Nevada. It was developed by a computer hacker group named "The Cult of the Dead Cow."

BO2K is a client/server application that can remotely controls an information processing application with a fixed IP (Internet Protocol) address by hiding it presence from the victim machine. After its installation, BO2K gathers information, performs system commands, reconfigures machines, and redirects network traffic to unauthorized services.

This RAT should be installed by the end user, and then it will perform its function unknowingly to the user. The B02K installation involves two separate operation, including the client and server .The server part should is an executable one and normally comes in the bo2k.exe name.

B02K has a configuration interface, which can be used to setup the functionality of the program. The configuration interface can be used to setup the Server file, network protocol including TCP or UDP, Port number, encryption mechanism, and password encryption key.

B02K client interface has a list of servers that displays the list of compromised servers and this server has its name, IP address, and connection information. Several commands can be used to gather data from victim machine and this command can be executed using the attacker machine by giving the intended parameters. The responses can be seen using the Server Response window.

  • Bandook RAT

Bandook RAT has the ability of process injection, API unhooking, bypass the Windows firewall etc. In this, the client has the ability to extend the functionality of the server by sending plugin code to it. The server has capability to hide it by creating a process using the default browser settings.

Bandook has been programmed using a combination of C++ and Delphi. It doesn't uses any cryptographic methods to encrypt, but uses a XORing method. In this, the server part is installed on System32 folder on Windows OS and on its execution; it establishes a connection to attacker, listen for incoming connections on the specified port. Then the attacker can execute the specified server command on the victim's machine. It has spying features like screen manager with screen clicks, cam manager that supports system with multiple cams, live key logger, cache reader, screen recorder etc.

The server component (28,200 bytes) is dropped under Windows, System32 or Program Files, Applications folders, the default name is ali.exe. Once the server component is run, it establishes a connection to the attacking client that listens for incoming connections on a configurable port to allow the attacker to execute arbitrary code from a computer.

  • ProRAT

ProRAT is a Remote Access Trojan that contains the client and server architecture. It operates by opening a port on the computer that allows attacker to execute several commands on the victim's machine. This RAT has the capability of logging keystrokes, stealing passwords, taking screen shots, view webcam, download and run files etc.

This RAT has features that enable them to undetected from antivirus and firewall; it can run stealthily on the background. It also has the ability to disable and delete system restore points, removing security software, displaying error messages etc.

  • Sub7 RAT

Sub7 RAT executes on the machine in an undetected and unauthorized manner. Sub7 worked on Windows 9x to Windows XP range OS. Sub7 also has the same architecture of other RAT and allows an attacker to execute server side commands and gain access and information.

One of the distinguished features of Sub7 RAT is that, it has an address book that allows the attacker to whether the victim's computer is online or not.

On the client-side the software had an "address book" that allowed the controller to know when the target computers are online. Additionally the server program could be customized before being delivered by a so-called server editor. A major incident related with Sub7 is that a hacker distributed a mail as that tricked the users to download the RAT and made them compromised.

  • njRAT

The remote access Trojan is thorough in its data-stealing capabilities. Beyond dropping a key logger, variants are capable of accessing a computer's camera, stealing credentials stored in browsers, opening reverse shells, stealing files, manipulating processes and viewing the user's desktop.

The malware is delivered via spear phishing emails, or drive-by downloads. The attackers are also embedding the malware in other applications such as the L517 Word List Generator; the malware is compressed and obfuscated by a number of tools in order to avoid detection by security software.

Once a victim is infected, the malware is also capable of scanning for other machines on the same network looking for other vulnerable machines to infect. Using that ability to move once inside a network coupled with the legitimate credentials and other data it harvests via its key logging capabilities, njRAT is a classic APT-style attack tool.

The malware stores keystrokes in a .tmp file and connects to a control server over port 1177 registered to an IP address in Gaza City, Palestine. A copy of the malware is stored in a second directory built by the attacker in order for it to execute again upon reboots. Once it connects to the command and control server, it sends system information including the computer name, attacker identifier, system location, operating system information, whether the computer contains a built-in camera, and which windows are open.

  • PoisonIvy

Poison Ivy is a remote access tool that include features common to most Windows-based RATs, including key logging; screen capturing, video capturing, file transfers, system administration, password theft, and traffic relaying.

The Poison Ivy builder kit allows attackers to customize and build their own PIVY server, which is delivered as mobile code to a target that has been compromised, typically using social engineering. Once the server executes on a compromised machine, it connects to a PIVY client installed on the attacker's machine, giving the attacker control of the compromised system.

In 2011, attackers used the RAT to compromise security firm RSA and steal data about its SecureID authentication system. Same year, PIVY also played a key role in the campaign known as Nitro that targeted chemical makers, government agencies, defense contractors, and human rights groups. Just recently, PIVY was the payload of a zero-day exploit in Internet Explorer used in what is known as a "strategic web compromise" attack against visitors to a U.S. government website and a variety of others.

Poison Ivy uses TCP for communication and it is encrypted using Camellia cipher using a 256 key. The key is made from a password created by the attacker while the PIVY server is built.

Many hacker groups used PoisonIvy to attack different category of targets across the world. These include a group called admin@338, which specializes in attacks targeting the financial services industry; th3bug focused on universities and healthcare facilities since 2009. The hacker group menuPass has run cyber-espionage attacks against defense contractors over the last four years

Organizational policy requirements for RAT

Remote Administration Tools provide a great assist in IT related works in organizational level. Staff from remote locations can access the computer and can work as if on the same location. These are the organizational level policy requirement for using Remote Administration Tools.

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  • All remote access tools that allow communication to and from the Internet must require multi-factor authentication.
  • The Remote Administration Tools authentication database source should be of AD or LDAP, and the authentication protocol must involve a challenge-response protocol.
  • Remote access tools must support the application layer proxy rather than direct connections through the perimeter firewall.
  • It should support strong, end-to-end encryption of the remote access communication channels as specified in the network encryption protocols policy.
  • All antivirus, data loss prevention, and other security systems must not be disabled, interfered with, or circumvented in any way.
  • Remote Administration Tools must be procured through the standard procurement process, and the IT group must approve the purchase.


Ryan Mazerik
Ryan Mazerik

Ryan has over 10yrs of experience in information security specifically in penetration testing and vulnerability assessment. He used to train and mentor consultants of these offerings to expand security delivery capabilities.He has strong passion in researching security vulnerabilities and taking sessions on information security concepts.