RSS feed source: US Computer Emergency Readiness Team

Summary

The Cybersecurity and Infrastructure Security Agency (CISA) and U.S. Coast Guard (USCG) are issuing this Cybersecurity Advisory to present findings from a recent CISA and USCG hunt engagement. The purpose of this advisory is to highlight identified cybersecurity issues, thereby informing security defenders in other organizations of potential similar issues and encouraging them to take proactive measures to enhance their cybersecurity posture. This advisory has been coordinated with the organization involved in the hunt engagement.

CISA led a proactive hunt engagement at a U.S. critical infrastructure organization with the support of USCG analysts. During hunts, CISA proactively searches for evidence of malicious activity or malicious cyber actor presence on customer networks. The organization invited CISA to conduct a proactive hunt to determine if an actor had been present in the organization’s environment. (Note: Henceforth, unless otherwise defined, “CISA” is used in this advisory to refer to the hunt team as an umbrella for both CISA and USCG analysts).

During this engagement, CISA did not identify evidence of malicious cyber activity or actor presence on the organization’s network, but did identify cybersecurity risks, including:

Insufficient logging; Insecurely stored credentials; Shared local administrator (admin) credentials across many workstations; Unrestricted remote access for local admin accounts; Insufficient network segmentation configuration between IT and operational technology (OT) assets; and Several device misconfigurations.

In

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RSS feed source: US Computer Emergency Readiness Team

Summary

Note: This joint Cybersecurity Advisory is part of an ongoing #StopRansomware effort to publish advisories for network defenders that detail various ransomware variants and ransomware threat actors. These #StopRansomware advisories include recently and historically observed tactics, techniques, and procedures (TTPs) and indicators of compromise (IOCs) to help organizations protect against ransomware. Visit stopransomware.gov to see all #StopRansomware advisories and to learn more about other ransomware threats and no-cost resources.

The Federal Bureau of Investigation (FBI), Cybersecurity and Infrastructure Security Agency (CISA), Department of Health and Human Services (HHS), and Multi-State Information Sharing and Analysis Center (MS-ISAC)—hereafter referred to as “the authoring organizations”—are releasing this joint advisory to disseminate known Interlock ransomware IOCs and TTPs identified through FBI investigations (as recently as June 2025) and trusted third-party reporting.

The Interlock ransomware variant was first observed in late September 2024, targeting various business, critical infrastructure, and other organizations in North America and Europe. FBI maintains these actors target their victims based on opportunity, and their activity is financially motivated. FBI is aware of Interlock ransomware encryptors designed for both Windows and Linux operating systems; these encryptors have been observed encrypting virtual machines (VMs) across both operating systems. FBI observed actors obtaining initial access via drive-by download from compromised legitimate websites, which is an uncommon method among ransomware groups. Actors were also observed using

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RSS feed source: US Computer Emergency Readiness Team

Summary

The Cybersecurity and Infrastructure Security Agency (CISA) is releasing this advisory in response to ransomware actors leveraging unpatched instances of a vulnerability in SimpleHelp Remote Monitoring and Management (RMM) to compromise customers of a utility billing software provider. This incident reflects a broader pattern of ransomware actors targeting organizations through unpatched versions of SimpleHelp RMM since January 2025.

SimpleHelp versions 5.5.7 and earlier contain several vulnerabilities, including CVE-2024-57727—a path traversal vulnerability.1 Ransomware actors likely leveraged CVE-2024-57727 to access downstream customers’ unpatched SimpleHelp RMM for disruption of services in double extortion compromises.1 

CISA added CVE-2024-57727 to its Known Exploited Vulnerabilities (KEV) Catalog on Feb. 13, 2025.

CISA urges software vendors, downstream customers, and end users to immediately implement the Mitigations listed in this advisory based on confirmed compromise or risk of compromise.

Download the PDF version of this report:

AA25-163A Ransomware Actors Exploit Unpatched SimpleHelp Remote Monitoring and Management to Compromise Utility Billing Software Provider (PDF, 420.49 KB ) Mitigations

CISA recommends organizations implement the mitigations below to respond to emerging ransomware activity exploiting SimpleHelp software. These mitigations align with the Cross-Sector Cybersecurity Performance Goals (CPGs) developed by CISA and the National Institute of Standards and Technology (NIST). The CPGs provide a minimum set of practices and protections that CISA and NIST recommend all organizations implement. CISA and

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RSS feed source: US Computer Emergency Readiness Team

Summary

The Federal Bureau of Investigation (FBI) and the Cybersecurity and Infrastructure Security Agency (CISA) are releasing this joint advisory to disseminate known tactics, techniques, and procedures (TTPs) and indicators of compromise (IOCs) associated with threat actors deploying the LummaC2 information stealer (infostealer) malware. LummaC2 malware is able to infiltrate victim computer networks and exfiltrate sensitive information, threatening vulnerable individuals’ and organizations’ computer networks across multiple U.S. critical infrastructure sectors. According to FBI information and trusted third-party reporting, this activity has been observed as recently as May 2025. The IOCs included in this advisory were associated with LummaC2 malware infections from November 2023 through May 2025.

The FBI and CISA encourage organizations to implement the recommendations in the Mitigations section of this advisory to reduce the likelihood and impact of LummaC2 malware.

Download the PDF version of this report:

AA25-141B Threat Actors Deploy LummaC2 Malware to Exfiltrate Sensitive Data from Organizations (PDF, 1.28 MB )

For a downloadable copy of IOCs, see:

AA25-141B STIX XML (XML, 146.54 KB ) AA25-141B STIX JSON (JSON, 300.90 KB ) Technical Details

Note: This advisory uses the MITRE ATT&CK® Matrix for Enterprise framework, version 17. See the MITRE ATT&CK Tactics and Techniques section of this advisory for threat actor activity mapped to MITRE ATT&CK

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