Microsoft Build Engine Used for File-Less Malware Attacks

  • By Dawna M. Roberts
  • Published: May 21, 2021
  • Last Updated: Mar 18, 2022

 New tactics are used every day by hackers trying to get a foot in the door using malware to take over victims’ computers. Another in an endless sea of options is using the Microsoft Build Engine (MBE) to filelessly deliver malware to targeted victims.

Research firm Anomali discovered the practice about a month ago and reported it on their website last Thursday. In their blog post, the company stated that ‘Anomali Threat Research discovered a campaign in which threat actors used MSBuild - a tool used for building apps and gives users an XML schema “that controls how the build platform processes and builds software” - to filelessly deliver RemcosRAT, and RedLine stealer using callbacks. The malicious MSBuild files we observed in this campaign contained encoded executables and shellcode, with some, hosted on Russian image-hosting site, “joxi[.]net.” While we were unable to determine the distribution method of the .proj files, the objective of these files was to execute either Remcos or RedLine Stealer. The majority of the samples we analyzed deliver Remcos as the final payload.’

The files are embedded with malicious code that allows these bad actors to install backdoors, take control of the victim’s machine, and steal personal/sensitive information for identity theft or fraud.

What is Microsoft Build Engine?

Microsoft’s Build Engine is an open-source tool used by .NET and Visual Studio developers. It is used for compiling source code, packaging, testing, and deploying applications.

According to The Hacker News “In using MSBuild to filelessly compromise a machine, the idea is to stay under the radar and thwart detection, as such malware makes use of a legitimate application to load the attack code into memory, thereby leaving no traces of infection on the system and giving attackers a high level of stealth.”

So far, only one infected file has been identified as malicious by antivirus/anti-malware software (“vwnfmo.lnk”). Another uploaded to VirusTotal on April 18 (“72214c84e2.proj”) cannot be detected as malicious by any antivirus/anti-malware software. Threat researchers have identified dozens of infected files that do not appear as malicious when tested using threat resources.

The Hacker News warns that “The majority of the samples analyzed by Anomali were found to deliver the Remcos RAT, with a few others also delivering the Quasar RAT and RedLine Stealer.”

What is the Threat?

Once installed, Remcos (Remote Control and Surveillance software) takes complete control of the machine, allowing the remote user to record keystrokes, access microphones, and webcams. Quasar is used for keylogging and password stealing. The threat known as Redline Stealer compromises machines by stealing credentials from browsers, VPNs, messaging programs, and hijacking cryptocurrency wallets.

Anomali threat researchers Tara Gould and Gage Male commented that “The threat actors behind this campaign used fileless delivery as a way to bypass security measures, and this technique is used by actors for a variety of objectives and motivations. This campaign highlights that reliance on antivirus software alone is insufficient for cyber defense, and the use of legitimate code to hide malware from antivirus technology is effective and growing exponentially.”

How Can Developers Stay Safe?

Now that this news is out there, Microsoft will take action to secure all files available in the MBE. However, as a developer, never download files from untrusted sources. Review the code within the files before executing files or installing anything. Additionally, take these steps to stay safe:

  • Keep strong passwords on all your devices.
  • Never reuse passwords.
  • Run good, strong antivirus/anti-malware on all your machines.
  • Never click links in email or download attachments.
  • Keep up with trending news of recent threats.
About the Author
IDStrong Logo

Related Articles

Instagram Vulnerability Allowed Hackers Access to Control Your Phone

Security experts Check Point Research discovered a critical vulnerability while examining Instagra ... Read More

Alien Malware Infects More than 226 Mobile Apps and Steals Bank Data

As reported on September 24, 2020, by ZDNet and ThreatPost, a new strain of malware named “A ... Read More

Universal Health Systems Hit by Ransomware Attack

Universal Health Systems (UHS), a Fortune 500 company owning more than 400 hospitals across the co ... Read More

Exchange Server Bug Exposes a Big Risk to Hackers

Months after Microsoft released a patch to fix a serious flaw in MS Exchange Server, more than 61% ... Read More

Clients’ Bank Data Exposed in Blackbaud Ransomware Attack

Blackbaud software was victim to a ransomware attack last May, and new information suggests that c ... Read More

Latest Articles

What You Need to Know about the Episource Data Breach

What You Need to Know about the Episource Data Breach

Episource is a California-based healthcare services and technology company that provides risk adjustment and medical coding services to healthcare plans, doctors, and several other types of healthcare organizations.

What you need to know about the Krispy Kreme Data Breach

What you need to know about the Krispy Kreme Data Breach

The popular doughnut and coffeehouse chain Krispy Kreme was established in 1937 in Winston-Salem, North Carolina. It has grown over the years and currently operates 1,500 shops and 17,900 points of access in 40 nations.

What You Need to Know about the Ocuco Data Breach

What You Need to Know about the Ocuco Data Breach

Ocuco is a Dublin-based organization that specializes in optical software solutions. Established in 1993 by Leo Mac Canna, the company initially developed software for independent optometrists.

What You Need to Know about the TxDOT Data Breach

What You Need to Know about the TxDOT Data Breach

The Texas Department of Transportation (TxDOT) is responsible for designing, planning, operating, building, and maintaining the state's transportation system to deliver a reliable and safe transportation system.

What You Need to Know about the AT&T Data Breach

What You Need to Know about the AT&T Data Breach

AT&T, one of the largest telecommunications providers in the United States and the fourth-largest telecommunications company in the world by revenue, experienced a significant data leak, which became public in June 2025.

What You Need to Know about the Mainstreet Bank Data Breach

What You Need to Know about the Mainstreet Bank Data Breach

MainStreet is a community-oriented bank in Fairfax, Virginia. Established in 2004, it is under the MainStreet Bancshares Incorporated, a small-cap financial holding organization.

Featured Articles

How to Buy a House with Bad Credit

How to Buy a House with Bad Credit

Buying your own home is the American Dream, but it might seem out of reach to those with bad credit. However, the good news is, if your credit is less than perfect, you do still have options and in most cases, can still buy a home.

How Secure Is Your Password? Tips to Improve Your Password Security

How Secure Is Your Password? Tips to Improve Your Password Security

Any good IT article on computers and network security will address the importance of strong, secure passwords. However, the challenge of good passwords is that most people have a hard time remembering them, so they use simple or obvious ones that pose a security risk.

Top 10 Senior Scams and How to Prevent Them

Top 10 Senior Scams and How to Prevent Them

Senior scams are becoming a major epidemic for two reasons. First, seniors often have a lot of money in the bank from a life of working hard and saving.

Notice

By proceeding with this scan, you agree to let IDStrong run a Free Scan of supplied parameters of your personal information and provide free preliminary findings in compliance with our Terms of Use and Privacy Notice. You consent to us using your provided information to complete the Free Scan and compare it against our records and breach databases or sources to provide your Free preliminary findings report.

Rest assured: IDStrong will not share your information with third parties or store your information beyond what is required to perform your scan and share your results.

Free Identity Threat Scan
Instantly Check if Your Personal Information is Exposed
All fields below are required
Please enter first name
Please enter last name
Please enter a city
Please select a state
Please enter an age
Please enter an email address
Close