Pupy RAT | |
Type of Malware | Trojan |
Targeted Countries | China |
Addittional Names | Pupy |
Associated Groups | APT33 |
Date of initial activity | 2017 |
Motivation | Cyberwarfare |
Attack Vectors | Software Vulnerabilities |
Targeted Systems | Windows |
Overview
Pupy RAT is a powerful and versatile Remote Access Trojan (RAT) that has been used by cybercriminals and threat groups to conduct covert operations on compromised systems. Originally written in Python, Pupy RAT is highly flexible, designed to provide attackers with full remote control over infected machines. Its capabilities allow threat actors to perform a wide range of malicious actions, from stealing sensitive data to deploying additional payloads or maintaining persistent access within a compromised network. With its ability to execute in-memory operations and reflective DLL loading, Pupy RAT can avoid detection by traditional file-based antivirus solutions, making it an attractive tool for cybercriminals and state-sponsored hackers alike.
The Trojan is often distributed through social engineering techniques, such as phishing emails containing malicious attachments, which are disguised as legitimate files, like job resumes or cryptocurrency lures. Once a victim interacts with the malicious file, it activates the RAT and establishes a backdoor into the system. This backdoor allows attackers to execute commands remotely, steal confidential information, and control the infected system without the user’s knowledge. Its stealth capabilities also make it difficult for conventional detection methods to spot the malware, allowing attackers to maintain access for extended periods.
Targets
Information
Individuals
How they operate
Initial Infection and Execution
The infection chain for Pupy RAT typically begins with social engineering tactics, such as phishing emails containing malicious attachments or links. Once the victim interacts with the malicious attachment, usually a .lnk file or a malicious document, the RAT payload is delivered to the system. The .lnk file is a shortcut that, when executed, loads a DLL loader into memory, which in turn executes the Pupy RAT binary. The malware can also be distributed via other techniques such as exploiting known vulnerabilities in software or systems.
Upon execution, Pupy RAT uses Python to run its malicious code, leveraging the language’s flexibility to establish communication with its command-and-control (C2) server. A distinctive feature of Pupy RAT is its use of reflective DLL injection and in-memory execution. These techniques help the malware avoid being written to disk, reducing the chances of detection by traditional security tools. The malware executes within the victim’s system memory, using the Windows API to load the malware and execute its payload silently.
Functionality and Capabilities
Once the malware is up and running, it provides attackers with a wide range of capabilities for controlling the victim machine. Pupy RAT enables remote desktop control, allowing attackers to interact with the system as though they were sitting in front of it. Additionally, it can record keystrokes, capture screenshots, and monitor system activity to gather intelligence about the victim’s behavior and environment. This functionality is particularly valuable for attackers who seek to steal sensitive data, including login credentials and intellectual property.
Pupy RAT also provides attackers with the ability to execute arbitrary commands on the compromised system. This could range from running system commands to uploading and downloading files. The malware’s reverse shell capability allows attackers to send commands to the victim system, bypassing network defenses. Since it is typically designed to run as a Python script, it can easily be modified to accommodate different attack scenarios or payloads, making it highly adaptable for various malicious operations.
Evasion and Persistence Techniques
One of the main reasons Pupy RAT is so effective is its use of advanced evasion techniques. The malware is capable of executing commands and scripts that help it evade detection by traditional endpoint security tools. For instance, by using reflective DLL injection, the RAT can run its payload directly in memory without leaving traces on the disk. This significantly reduces the likelihood of antivirus or security software detecting the infection.
To further evade detection, Pupy RAT can modify system settings, such as altering the Windows registry or creating scheduled tasks, to ensure it persists even after system reboots. The malware may also use fileless techniques to remain hidden and bypass security measures designed to detect file-based malware. These techniques are effective in making the RAT difficult to analyze or remove.
Communication with Command and Control Servers
Pupy RAT is capable of maintaining a covert connection with its C2 server over encrypted channels. This communication is essential for the attacker to issue commands and receive data from the infected system. The C2 server can send instructions that allow the attacker to adjust the malware’s behavior, deliver additional payloads, or exfiltrate sensitive data. Communication is often conducted over HTTP/S or custom protocols, which can help to disguise the traffic as legitimate web traffic, making it harder for network defenses to detect.
To further strengthen its communication, Pupy RAT can use proxy chains or VPNs to obscure the origin of the attack, ensuring that the attacker’s true location remains hidden. This is particularly useful in APT scenarios where attackers seek to maintain anonymity and prevent tracebacks that could lead to attribution.
Lateral Movement and Exfiltration
After successfully compromising a target system, Pupy RAT can be used to move laterally within the network. It can exploit existing network configurations and remote services, such as RDP (Remote Desktop Protocol) or SMB (Server Message Block), to propagate across the network. By executing commands or uploading additional tools, attackers can use Pupy RAT to compromise more systems, ultimately gaining greater control over the entire infrastructure.
Exfiltration is another key feature of Pupy RAT. The malware can gather sensitive information, such as user credentials, personal files, and confidential data, and transmit it back to the attacker’s C2 server. This is often done over the same covert channel used for command communication, ensuring that the stolen data can be securely exfiltrated without detection. In some cases, the data exfiltration can be automated, with the malware regularly uploading valuable files or information to the attacker.
MITRE Tactics and Techniques
1. Initial Access
Phishing (T1566): Pupy RAT is often distributed through phishing emails, which may contain malicious attachments (such as malicious .lnk files or infected documents), leading to an initial infection.
Exploitation for Initial Access (T1203): Vulnerabilities in applications or system configurations may be exploited by attackers to execute the malicious payload, triggering the installation of the RAT.
2. Execution
Command and Scripting Interpreter (T1059): Pupy RAT uses scripting languages such as Python to execute commands on the compromised system. This includes running malicious scripts or commands to interact with the RAT.
User Execution (T1204): The malware relies on users executing malicious files, such as malicious .lnk files disguised as harmless documents. This tactic enables the malware to run when the victim interacts with the infected file.
3. Persistence
Create or Modify System Process (T1543): Pupy RAT often establishes persistence by modifying system configurations or using scheduled tasks to maintain its access over time.
Boot or Logon Autostart Execution (T1547): The malware can leverage techniques like registry modifications or system startup scripts to ensure that it starts automatically upon system reboot or user login.
4. Privilege Escalation
Exploitation for Privilege Escalation (T1068): Attackers may use Pupy RAT to escalate their privileges on a compromised system by exploiting vulnerabilities to gain higher-level access.
5. Defense Evasion
Obfuscated Files or Information (T1027): Pupy RAT uses various evasion techniques, such as reflective DLL injection and in-memory execution, to avoid detection by traditional antivirus and endpoint protection tools.
Indicator Removal on Host (T1070): The RAT may delete or alter logs and traces of its activities on the infected system to avoid detection and maintain stealth.
Signed Binary Proxy Execution (T1218): Pupy RAT has the capability to execute signed binaries, enabling it to bypass security controls by leveraging trusted system processes for execution.
6. Credential Access
Credentials Dumping (T1003): Pupy RAT can gather credentials from the infected system, potentially extracting login information from memory or system files, allowing attackers to escalate their control or access other systems.
7. Discovery
System Information Discovery (T1082): The malware can query the system for information about the environment, such as OS version, user accounts, and other system configurations, to tailor its actions.
8. Lateral Movement
Remote Services (T1021): Pupy RAT can enable lateral movement by using remote services (such as RDP or SSH) to access other systems within the network, expanding its control across compromised systems.
9. Collection
Data from Information Repositories (T1213): Pupy RAT can be used to collect sensitive information, such as files, emails, or documents, from the compromised system.
10. Exfiltration
Exfiltration Over Command and Control Channel (T1041): Data exfiltration may occur via the same command-and-control (C2) channel used by Pupy RAT, allowing attackers to transmit stolen data out of the compromised network.
11. Impact
Data Encrypted for Impact (T1486): In some instances, Pupy RAT may be used in conjunction with other tools or malware to encrypt data or disrupt normal operations.
