May 2023’s Most Wanted Malware: New Version of Guloader Delivers Encrypted Cloud-Based Payloads

Check Point® Software Technologies Ltd. (NASDAQ: CHKP), a leading provider of cybersecurity solutions globally, has published its Global Threat Index for May 2023. Researchers reported on a new version of shellcode-based downloader GuLoader, which was the fourth most prevalent malware last month. With fully encrypted payloads and anti-analysis techniques, the latest form can be stored undetected in well-known public cloud services, including Google Drive. Meanwhile, Qbot and Anubis took first place on their respective lists, and Education/Research remained the most exploited industry.

The GuLoader malware, widely used by cybercriminals to bypass antivirus detection, has undergone significant changes. The latest iteration employs a sophisticated technique of replacing code in a legitimate process, facilitating its evasion from process monitoring security tools. The payloads are fully encrypted and stored undetected in renowned public cloud services, including Google Drive. This unique blend of encryption, raw binary format, and separation from the loader makes the payloads invisible to antivirus programs, posing a significant threat to users and businesses worldwide.

Last month also saw both Qbot and Anubis taking first place on their respective lists. Despite efforts to slow down malware distribution by blocking macros in Office files, Qbot operators have been quick to adapt their distribution and delivery. It has recently been seen abusing a dynamic link library (DLL) hijacking flaw in the Windows 10 WordPad program to infect computers.

“Public tools and services are increasingly being exploited by cybercriminals to deliver and store malware campaigns. The trustworthiness of a source no longer guarantees complete security,” said Maya Horowitz, VP Research at Check Point Software. “This highlights the urgent need for education on identifying suspicious activities. We strongly advise against disclosing personal information or downloading attachments unless the authenticity and benign nature of the request have been confirmed. Additionally, it’s crucial to have advanced security solutions like Check Point Horizon XDR/XPR in place, which can effectively identify if an allegedly benign behavior is actually malicious, providing an extra layer of protection against sophisticated threats.”

The Education/Research sector continues to be the most targeted industry, according to Check Point’s Index. The report also revealed that the “Web Servers Malicious URL Directory Traversal” vulnerability is the most exploited, impacting 49% of organizations globally. This is closely followed by “Apache Log4j Remote Code Execution” and “HTTP Headers Remote Code Execution” vulnerabilities, affecting 45% and 44% of organizations worldwide, respectively.

Top malware families

*The arrows relate to the change in rank compared to the previous month.

Qbot was the most prevalent malware last month with an impact of 6% worldwide organizations, followed by Formbook with a global impact of 5% and AgentTesla with a global impact of 3%.

1. ↑ Qbot –Qbot AKA Qakbot is a multipurpose malware that first appeared in 2008. It was designed to steal a user’s credentials, record keystrokes, steal cookies from browsers, spy on banking activities, and deploy additional malware. Often distributed via spam email, Qbot employs several anti-VM, anti-debugging, and anti-sandbox techniques to hinder analysis and evade detection. Commencing in 2022, it emerged as one of the most prevalent Trojans.
2. ↑ Formbook – Formbook is an Infostealer targeting the Windows OS and was first detected in 2016. It is marketed as Malware as a Service (MaaS) in underground hacking forums for its strong evasion techniques and relatively low price. FormBook harvests credentials from various web browsers, collects screenshots, monitors and logs keystrokes, and can download and execute files according to orders from its C&C.
3. ↓ AgentTesla – AgentTesla is an advanced RAT functioning as a keylogger and information stealer, which is capable of monitoring and collecting the victim’s keyboard input, system keyboard, taking screenshots, and exfiltrating credentials to a variety of software installed on a victim’s machine (including Google Chrome, Mozilla Firefox and the Microsoft Outlook email client).

Top Attacked Industries Globally

Last month, Education/Research remained in first place as the most exploited industry globally, followed by Government/Military and Healthcare.

1. Education/Research
2. Government/Military
3. Healthcare

Top exploited vulnerabilities

Last month, “Web Servers Malicious URL Directory Traversal” was the most exploited vulnerability, impacting 49% of organizations globally, followed by “Apache Log4j Remote Code Execution” impacting 45% of organizations worldwide. “HTTP Headers Remote Code Execution” was the third most used vulnerability, with a global impact of 44%.

1. ↔ Web Servers Malicious URL Directory Traversal – There exists a directory traversal vulnerability on different web servers. The vulnerability is due to an input validation error in a web server that does not properly sanitize the URI for the directory traversal patterns. Successful exploitation allows unauthenticated remote attackers to disclose or access arbitrary files on the vulnerable server.
2. ↔ Apache Log4j Remote Code Execution (CVE-2021-44228) – A remote code execution vulnerability exists in Apache Log4j. Successful exploitation of this vulnerability could allow a remote attacker to execute arbitrary code on the affected system.
3. ↔ HTTP Headers Remote Code Execution (CVE-2020-10826,CVE-2020-10827,CVE-2020-10828,CVE-2020-13756) – HTTP headers let the client and the server pass additional information with an HTTP request. A remote attacker may use a vulnerable HTTP Header to run arbitrary code on the victim machine.

Top Mobile Malwares

Last month Anubis rose to first place as the most prevalent Mobile malware, followed by AhMyth and Hiddad.

1. Anubis – Anubis is a banking Trojan malware designed for Android mobile phones. Since it was initially detected, it has gained additional functions including Remote Access Trojan (RAT) functionality, keylogger, audio recording capabilities and various ransomware features. It has been detected on hundreds of different applications available in the Google Store.
2. AhMyth – AhMyth is a Remote Access Trojan (RAT) discovered in 2017. It is distributed through Android apps that can be found on app stores and various websites. When a user installs one of these infected apps, the malware can collect sensitive information from the device and perform actions such as keylogging, taking screenshots, sending SMS messages, and activating the camera, which usually used to steal sensitive information.
3. Hiddad – Hiddad is an Android malware which repackages legitimate apps and then releases them to a third-party store. Its main function is to display ads, but it can also gain access to key security details built into the OS.

Check Point’s Global Threat Impact Index and its ThreatCloud Map is powered by Check Point’s ThreatCloud AI: the brain behind Check Point’s security. ThreatCloud AI provides real-time threat intelligence derived from hundreds of millions of sensors worldwide, over networks, endpoints and mobiles. The intelligence is enriched with 40+ AI and Machine Learning technologies that identify and block emerging threats,and exclusive research data from Check Point Research, the intelligence and research arm of Check Point Software Technologies.

The complete list of the top ten malware families in May can be found on the Check Point blog.

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Check Point Research provides leading cyber threat intelligence to Check Point Software customers and the greater intelligence community. The research team collects and analyzes global cyber-attack data stored on ThreatCloud to keep hackers at bay, while ensuring all Check Point products are updated with the latest protections. The research team consists of over 100 analysts and researchers cooperating with other security vendors, law enforcement and various CERTs.

About Check Point Software Technologies Ltd. 

Check Point Software Technologies Ltd. (www.checkpoint.com) is a leading provider of cybersecurity solutions to corporate enterprises and governments globally. Check Point Infinity’s portfolio of solutions protects enterprises and public organizations from 5^th generation cyberattacks with an industry leading catch rate of malware, ransomware and other threats. Infinity comprises four core pillars delivering uncompromised security and generation V threat prevention across enterprise environments: Check Point Harmony, for remote users; Check Point CloudGuard, to automatically secure clouds; and Check Point Quantum, to protect network perimeters and datacenters, all controlled by the industry’s most comprehensive, intuitive unified security management; Check Point Horizon, a prevention-first security operations suite. Check Point protects over 100,000 organizations of all sizes.