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1436
IOCs

FormBook is a data stealer that is being distributed as a MaaS. FormBook differs from a lot of competing malware by its extreme ease of use that allows even the unexperienced threat actors to use FormBook virus.

Stealer
Type
Unknown
Origin
1 January, 2016
First seen
28 March, 2024
Last seen
Also known as
Xloader

How to analyze Formbook with ANY.RUN

Type
Unknown
Origin
1 January, 2016
First seen
28 March, 2024
Last seen

IOCs

Hashes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http://www.ellentscm.info/ob/
http://www.grupooceanique.com/ns03/
http://www.fight4yourhappiness.com/dd20/
http://www.georgiemakeup.com/dz11/
http://www.dpxj888.com/tt15/
http://www.kudochhattisgarh.org/pdac/
http://www.mandatoryonline.com/mo46/
http://www.gltip2le.shop/kh11/
http://www.posycbd.com/tdet/
http://www.rdlva.com/pz08/
http://www.dallasidpr.com/g2pa/
http://www.com-smdi-al-frsat.shop/fe15/
http://www.yoursweets.online/vr01/
http://www.lifeofthobes.uk/btrd/
http://www.quote2bill.com/6vmn/
http://www.a2zglobalimports.com/kmge/
http://www.stampingwithginny.com/dit6/
http://www.norjax.com/app/
http://www.worstig.com/w9z/
http://www.himebauch.live/5ogg/
Last Seen at

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What is FormBook malware?

FormBook stealer is an infostealer‍ trojan available as a malware-as-service. This malware is often used by attackers with low technical literacy and little programming knowledge. FormBook can be used to steal various information from infected machines.

Despite how easy it is to set up and use, the malware has advanced stealing and evasion functions including the ability to pull stored and recorded user input. In addition, the FormBook stealer is capable of searching for, viewing, and interacting with files, and taking screenshots. Even though the stealing capability of this virus can be considered somewhat average, its ease of operation, the injection schema, and a set of effective measures that the malware takes to avoid detection by antivirus software made FormBook a popular virus in the hacker community and, unfortunately, its popularity is only continuing to rise in 2019.

General description of the FormBook stealer

Written in C and x86 assembly language, FormBook is sold as a PHP control panel and can be purchased on highly accessible online forums for merely 30 dollars.

Uniquely, unlike the majority of existing viruses that exploit the latest vulnerabilities or zero-days, FormBook can inject into processes and set up function hooks utilizing already known issues. Hence the claim made by the makers, that the virus will work flawlessly regardless of the Windows version.

Together with its stealer functionality and evasion techniques, the virus knows how to execute instructions from a control server that includes starting new processes, their injection, and rebooting the victim’s PC. What’s more, the virus is able to record Windows’ ntdll.dll module into memory and call it directly, which makes API monitoring and user-mode hooking almost insufficient.

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FormBook malware analysis

A video simulation recorded on the ANY.RUN interactive malware analysis service allows us to take an in-depth look at the behavior of this clever virus and other malware such as Dridex and Lokibot with their elaborate anti-evasion techniques.

formbook execution process graph

Figure 1: Processes created by FormBook during execution as shown by ANY.RUN simulation

  • As shown by the ANY.RUN simulation, firstly the virus established connection to the CnC server;
  • After this, a malicious executable file, in this analysis's case pretending to be a .png is being dropped or overwritten and executed;
  • Then, FormBook proceeds to steal the personal data and change the autorun value in the registry. Also, the virus loads DLL from Mozilla Firefox creates files in the user directory, and starts CMD.EXE to set up persistence and later begin process injection;
  • Finally, injected Firefox.exe is executed for logging keystrokes, stealing clipboard data, and extracting authentication information from browser HTTP sessions.

Distribution of the FormBook stealer

According to FormBook analysis, malware is usually distributed via email campaigns that utilized a wide array of infecting mechanisms and can contain a number of various file attachments. Among the most commonly observed attachments are either PDFs, DOC or EXE, or ZIP, RAR, ACE, and ISO files.

Campaigns in which the virus is distributed through files with PDF extensions are known to utilize shipping-related themes and usually include a download link that points at the malicious code instead of the actual virus. DOC and EXE campaigns utilize macros to install and run the virus. Often, the virus is retrieved as a .PDF file in such a case. Finally, archive campaigns are considered to be the most common attack vector for this virus and usually revolve around a business-related theme, such as a payment order. In the case of this attack vector, attachments either contain a link to the FormBook stealer EXE file or install and run the virus on victims' PCs directly.

In 2020 Formbook has become quite popular as it used Covid-themed emails for decoys with subject headings such as “Government Response to Coronavirus Covid-19”.

FormBook execution process

Sandbox simulation performed on the ANY.RUN interactive malware hunting service allows us to detect and investigate the behavior of FormBook in a lot of detail.

text report of the formbook malware analysis

Figure 2: A text report generated by ANY.RUN

After downloading the malicious file the only thing needed to start the contamination is for the file to be opened. In a case when Microsoft Office file (doc, xls, rtf) is used as an infection source, after it is opened the malware exploits the CVE-2017-11882 vulnerability, thus Microsoft Office Equation Editor proceeds to download a malicious executable file and run it.

After infecting the victim's PC, the virus copies and renames itself into a directory that differs based on the privileges of the user. If an admin account is used, the virus installs itself in either %ProgramFiles% or %CommonProgramFiles%. On the other hand, if the privileges are not elevated, then the virus will copy itself into %TEMP% or %APPDATA.

Also, Formbook trojan changes the autorun value in the registry depending on is it was running with normal or elevated privileges. Next, the malware copies itself into a directory it proceeds to check if it’s being run on a virtual machine or analyzed, evaluating the best anti-evasion option that can be utilized in a particular situation. Meanwhile, the virus will try to evaluate the USERNAME environment variable to find out if it’s launched in simulation, while also checking for the presence of debuggers. It should be noted that the malware uses particularly clever techniques while performing an analysis, for example, all shared strings such as command server names are decoded only briefly if they are absolutely required, which makes FormBook highly elusive. In the next step, the virus uses the same injection method to an active explorer.exe process which is only employed as a non-permanent staging ground.

The virus occasionally performs injections into web browser processes and explorer.exe. After injecting into the process, the virus chooses a random application from a static list. Then, the virus proceeds to run the chosen application in suspended mode and copy itself in the address space of the suspended process, thus mimicking a genuine Microsoft process. Next, the virus exits the original process which leaves FormBook's dead code in explorer.exe as a result. From this stage, new FormBook processes can inject targeted applications like web browser processes, which in the case of this particular ANY.RUN simulation is Firefox.

Depending on the objective process, the virus can establish various function hooks. Being run from inside the context of an already generated process, the virus starts to go through every currently active process, trying to identify targeted programs. As soon as a target is found, FormBook will inject itself into it and install a particular set of API hooks, that are based on the target program. The data is then saved in files in the %APPDATA% directory until it is sent to the C&C server. Pay attention to this function to detect malware.

How to avoid infection by FormBook?

The best counteraction technique is to exhibit caution when receiving emails with attachments from unknown senders. Attackers usually use social engineering to trick victims into downloading and opening infected files.

Deleting any suspicious emails from the inbox is a good way to stay safe. If the infection is already detected, a good practice is to carry out an analysis of all devices connected to the network for established CnC or potentially malicious URL connections. Once a suspicious email is received, perimeter settings can be adjusted to block all related emails in the future. Finally, if an infected file is already downloaded, the host should be quarantined until the threat is completely mitigated.

How to detect Formbook using ANY.RUN?

Formbook trojan usually injects into explorer.exe and another processes from the list, such as firefox.exe and msiexec.exe. Knowing this malware's function you can take a look at the process tree after a while during execution and easily determine either the sample is Formbook or not.

formbook execution process tree Figure 3: A tree of processes created by Formbook during its execution

Conclusion

Thanks to extreme ease of use and low cost, FormBook is gaining traction in the criminal community. Not only is the virus's functionality freely accessible for download on open hacker forums and easy to set up without any programming knowledge, but it also comes equipped with some highly advanced anti-evasion techniques, that make detecting it with anti-virus software ultra-difficult. ANY.RUN interactive malware hunting service enables to study FormBook in detail from a secure environment and implement cybersecurity measures accordingly.

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