What is Agent Tesla malware?
Agent Tesla is a password stealer spyware that has been around since 2014. The malware can be used by attackers to spy on victims, allowing them to see everything that has been typed in supported programs and web-browsers.
Being marketed and sold on its own website, which falsely claims that the program is a legitimate keylogger created for personal use, Agent Tesla virus has become extremely popular in the hacker community. Not lastly due to its ease of use and tech support, available on the “official” website where this malware is being sold by the attackers, as well as on the dedicated Discord server. Despite claiming legitimacy of the software, support staff gives advice on utilizing the virus illegally. It is thought that Agent Tesla spyware has originated in Turkey.
General description of Agent Tesla
The spyware is created using .Net software framework. It is aimed at stealing personal data and transmitting it back to the C2 server. The malware is able to access information from web browsers, email clients and FTP servers.
In addition, Agent Tesla malware is able to capture screenshots and videos. It can also record clipboard information and form values. The virus was being distributed on agenttesla-dot-com where attackers could purchase it for as little as 15$. However, depending on the requested options the package price could easily reach roughly 70$.
Uniquely, creators of the malware have set up a sort of an ecosystem around the program, providing 24/7 customer support as well as pre-matched purchase plans that include various options tailored for different budgets and goals. The virus is supplied with a dedicated builder that has a simple-to-use control panel. It allows even a non-technically savvy attacker to pack the payload into a malicious document. What’s more, after 2015 the control panel of Agent Tesla has been expanded with extensive automation functionality, allowing the attacker to automatically capture snapshots or remotely activate the webcam on a victim’s PC in set intervals.
The malware comes equipped with multiple persistence mechanisms that help it avoid antivirus detection. As such, it can resume operation automatically after a system reboot. It is also able to turn off Windows processes to stay hidden.
Malware analysis of Agent Tesla
Interactivity of ANY.RUN allows tracking activities in real-time and watching Agent Tesla in action in a controlled, safe environment with full real-time access to the sandbox simulation. A video recorded by the ANY.RUN gives us the ability to take a closer look at the lifecycle of this virus.
Figure 1: A lifecycle graph generated by ANY.RUN
How to avoid infection by Agent Tesla?
Agent Tesla malware is not an easy one to detect. The most robust way to stay safe is to exhibit caution when opening suspicious emails or visiting unknown links. Above all, one must be careful to download attachments in emails from unknown senders.
Distribution of Agent Tesla
The malware is distributed at large via spam email campaigns. It is usually delivered to victims in malicious documents, or via malicious web-links. Upon visiting such a link, a contaminated document will be automatically downloaded to a victim’s PC.
If opened, the document will trigger the download of the actual virus. The spyware saves itself in “%temp%” folder and then automatically executes. Email campaigns usually target individuals working in different industries. Topics of malicious emails can be extremely diverse.
Agent Tesla execution process
Agent Tesla keylogger is mostly spread via Microsoft Word documents that contain an embedded executed file or exploit. Once clicked, an executable file is downloaded and renamed. The downloaded file runs itself and creates a child process which in turn can create another child process.
The malware is able to use Regsvcs and Regasm to proxy the code execution through a trusted Windows utility. In the given example RegSvcs.exe process is stealing the personal data.
Figure 2: A process tree of the Agent Tesla execution
Since the main purpose of Agent Tesla RAT is stealing personal information you can define it by behavioral activities. To do so take a look at the indicators of a malicious process (most often its an injected "RegAsm.exe"). If there are the indicator "Actions looks like stealing of personal data" in "Process details" section you probably are dealing with the Agent Tesla trojan. Also, you can view what information the malware has stolen by clicking on the indicator. You can navigate through by clicking right and left arrows in the appeared window.
How to get more Agent Tesla data using ANY.RUN?
Often Agenttesla packets encryption unsuccessful and with ANY.RUN's "Network Stream" analysts can take a look at what data this malware stole. To do it open "Connections" tab in the lower part of the task's window and simply click on the connection which sent data. Not unusual that you can find inside this information even attacker’s SMTP credential.
Figure 2: Agent Tesla’s Network stream without encryption
Conclusion
According to available information, since its creation, Agent Tesla trojan has been used by over 6,300 customers. Unfortunately, the popularity of the virus is only continuing to rise. The upward trend is of, course, supported by the ease of use which allows even novice attackers to set up attacks.
A company-like service provided by the virus creators also plays a significant role. The danger of Agent Tesla lies not only in the fact that it can be used by almost anybody but also in its ability to open doors to more destructive viruses. Thankfully, interactive analysis services such as ANY.RUN allows professionals to examine the malware behavior in detail and set up appropriate security responses.
