Internet Security Report: Fileless Malware on the Rise, Defenses Failing

Seventy-five percent of malware is going undetected by “traditional malware solutions,” according to a new report. And 74% of threats detected in the last quarter were zero-day malware, an all-time high, according to the researchers.

The report, the Internet Security Report for Q1 2021 from WatchGuard Technologies, found that malicious scripts are delivering fileless malware in the form of an XML external entity. The most widespread was XML.JSLoader, which made the top 10 for the first time in the first quarter of 2021. According to researchers: “The sample WatchGuard identified uses an XML external entity (XXE) attack to open a shell to run commands to bypass the local PowerShell execution policy and runs in a non-interactive way, hidden from the actual user or victim. This is another example of the rising prevalence of fileless malware and the need for advanced endpoint detection and response capabilities.”

A ransomware loader called Zmutzy made the top 2 in Q1. It manifests as a disguised email attachment. According to the researchers: “Associated with Nibiru ransomware specifically, victims encounter this threat as a zipped file attachment to an email or a download from a malicious website. Running the zip file downloads an executable, which to the victim appears to be a legitimate PDF. Attackers used a comma instead of a period in the file name and a manually adjusted icon to pass the malicious zip file off as a PDF. This type of attack highlights the importance of phishing education and training, as well as implementing back-up solutions in the event that a variant like this unleashes a ransomware infection.”

The report highlighted a number of other trends in malware and network attacks as well.

  • Half of the top-10 malware families by volume were new to the top-10, including Ursu, Trojan.IFrame, XML.JSLoader, Zmutzy, and Zum.Androm;

  • Encrypted connections saw less zero-day malware (60.3%) than the overall average (74%);

  • Network attacks reached a three-year high during the first quarter, at 4.2 million Intrusion Prevention Service (IPS) hits on Firebox appliances;

  • More than 5 million malicious domains were blocked by DNSWatch in the quarter, a 281% increase over Q4 2020.

  • Exploits against ProxyLogin Exchange Server flaws increased 1,600%.

A complete report and executive summary can be downloaded here. An infographic with highlights from the report can be accessed here.

About the Author

David Nagel is the former editorial director of 1105 Media's Education Group and editor-in-chief of THE Journal, STEAM Universe, and Spaces4Learning. A 30-year publishing veteran, Nagel has led or contributed to dozens of technology, art, marketing, media, and business publications.

He can be reached at [email protected]. You can also connect with him on LinkedIn at https://www.linkedin.com/in/davidrnagel/ .


Featured

  • school building protected by a glowing blue shield with circuit patterns, blocking red-orange cyber threat icons

    Establishing a Proactive Defense Against Evolving Cyber Threats

    Here are six good starting points for K-12 districts that want to improve their cybersecurity mitigation strategies and take a more proactive approach to mitigating risk.

  • Stylized illustration showing cybersecurity elements like shields, padlocks, and secure cloud icons on a neutral, minimalist digital background

    Microsoft Announces Host of Security Advancements

    Microsoft has announced major cybersecurity advancements across its product portfolio and practices. The work is part of its Secure Future Initiative (SFI), a multiyear cybersecurity transformation the company calls the largest engineering project in company history.

  • soft-edged digital blocks and AI imagery on a muted background

    OpenAI Launches GPT-4.1, Offering Upgrades in Coding, Context Processing, Efficiency

    OpenAI has introduced GPT-4.1, offering stronger performance across software development, instruction following, and long-context comprehension.

  • The AI Show

    Register for Free to Attend the World's Greatest Show for All Things AI in EDU

    The AI Show @ ASU+GSV, held April 5–7, 2025, at the San Diego Convention Center, is a free event designed to help educators, students, and parents navigate AI's role in education. Featuring hands-on workshops, AI-powered networking, live demos from 125+ EdTech exhibitors, and keynote speakers like Colin Kaepernick and Stevie Van Zandt, the event offers practical insights into AI-driven teaching, learning, and career opportunities. Attendees will gain actionable strategies to integrate AI into classrooms while exploring innovations that promote equity, accessibility, and student success.