Microsoft tracked over 30 MacSync Stealer domains by focusing on behavioral patterns, revealing a campaign targeting passwords, keys, wallets and other data. Domain blocking is a losing game when the thing you’re blocking can register a new domain faster than you can add it to a list. That’s the exact problem Microsoft Defender Experts ran into while tracking MacSync Stealer, a macOS-focused information stealer that RST Cloud first flagged for swapping out its command-and-control infrastructure almost immediately after getting publicly outed. Microsoft detailed how its experts stopped chasing individual domains and started tracking the behaviors that stayed constant underneath them. Instead of tracking individual domains, Microsoft looked at recurring request patterns, HTTP headers and other behaviors. This allowed its researchers to link more than 30 domains to the same campaign and determine that the infrastructure was doing more than just sending commands to infected Macs. It was also being used to collect, stage and exfiltrate stolen data. “MacSync Stealer is a macOS-focused information stealer that relies on changing infrastructure to deliver payloads, communicate with compromised devices, and exfiltrate data. Earlier reporting by RST Cloud identified the threat through a limited set of domains and documented rapid command-and-control (C2) replacement after public disclosure.” reads the report published by Microsoft. “Microsoft Defender Experts expanded that view by correlating recurring endpoints and network behaviors across the activity. This behavior-led approach connected more than 30 domains and showed that the infrastructure supported more than C2 communication, extending into active collection, staging, and exfiltration.” The infection chain starts with a trick rather than an exploit. Victims get social-engineered through a technique known as ClickFix, tricked into pasting or running commands directly in macOS Terminal, and once that shell session fires, curl pulls down attacker-controlled payload content from a path formatted as /curl/[token]. Then, native macOS tools decode and unpack the payload, and an AppleScript-driven layer takes over, blending Unix commands like sh, cp, rm, and killall with osascript calls that make the whole chain look more like ordinary system scripting than malware. Once active, the stealer focuses on valuable data. The malicious code looks for macOS Keychain data, saved browser passwords and cookies, SSH keys, AWS credentials, Kubernetes configurations and files in common user folders. It also searches for Ledger and Trezor wallet data, showing that the malware targets users with valuable credentials and assets rather than simply collecting random browser history. What actually confirms exfiltration, rather than just suspicious traffic, is the upload mechanism itself. Collected data gets staged under temporary paths, compressed into an archive, split into chunks, and pushed out through HTTP PUT requests carrying parameters like upload_id, chunk_index, and total_chunks. “The staged archive was uploaded through rotating infrastructure using curl and HTTP PUT requests. Observed requests included –data-binary, API-key headers, macOS User-Agent string, upload_id values, chunk_index values, and total_chunks parameters.” states Microsoft. “These upload traits confirmed active data exfiltration and provided durable hunting pivots even when domains rotated. “ The researchers pointed out that the exfiltration method stays recognizable even when the destination keeps changing. RST Cloud’s follow-up work backs up how consistent this infrastructure actually is under the surface. Using the same recurring URI patterns, RST Cloud surfaced eleven additional candidate domains and found a static API-key value shared across four confirmed command-and-control domains, even while the build token attached to each deployment kept rotating. A shared static key sitting inside otherwise rotating infrastructure is exactly the kind of detail that makes automated evasion look less impressive up close. The attack wraps up with cleanup, deleting temporary archives, staging folders, and lock files after the upload completes. Microsoft notes this reduces what’s left sitting on disk, but it doesn’t erase the behavioral sequence itself. “After exfiltration, the malware removed temporary archives, staging folders, lock files, and other artifacts. Although this cleanup reduced on-disk evidence, the sequence of archive creation, chunked upload, and deletion can still provide a useful behavioral correlation for defenders.” concludes Microsoft. For anyone defending Mac fleets, the practical takeaway here isn’t a list of domains to block, since that list will be stale within days. It’s building detection around the recurring shape of the attack itself: shell sessions spawning curl with those specific flag patterns, osascript chaining rapidly into network activity, and archives appearing under /tmp/sync* right before outbound PUT traffic starts. Chase the pattern, not the address, because the address was never going to sit still long enough to matter. Follow me on Twitter: @securityaffairs and Facebook and Mastodon Pierluigi Paganini (SecurityAffairs – hacking, malware)
The Cybersecurity and Infrastructure Security Agency (CISA) said Tuesday that the Medusa ransomware gang has breached more than 500 critical infrastructure organizations in the United States since June 2021. This was revealed in a joint advisory in coordination with the Department of Health and Human Services (HHS) and the Federal Bureau of Investigation (FBI). "As of April 2026, Medusa actors have impacted more than 500 victims across multiple critical infrastructure sectors, including Healthcare and Public Health, Defense Industrial Base, Critical Manufacturing, Government Services and Facilities, Information Technology, and Financial Services," they said. "Other victims include organizations in the medical, education, legal, insurance, technology, and manufacturing industries." This is an update to a joint report published in March 2025, which said the Medusa ransomware operation had impacted an estimated over 300 critical infrastructure organizations.
A Heights Finance breach exposed personal and financial data of over 1.2 million people after hackers compromised a third-party cloud platform. Heights Finance is a U.S. consumer finance company that provides personal loans and related lending services, mainly to customers who may have limited access to traditional bank credit. It is part of Heights Finance Holdings Co. Heights Finance Holdings is notifying more than 1.2 million people that on May 7, 2026, Heights Finance discovered unauthorized access to a third-party cloud platform storing customer data. The company launched an investigation with external cybersecurity experts and notified federal law enforcement. “On May 7, 2026, Heights discovered that an unauthorized actor gained access to a cloud-based platform hosted by a third party that we use to store certain customer data. This activity was limited to the cloud-based platform only—it did not affect any of our loan management systems or other computer systems or networks. We immediately activated our incident response protocols, brought in outside cybersecurity specialists to investigate, and reported the incident to federal law enforcement.” reads the notice of data breach. “We have since confirmed that the cloud-based platform is secure and that there is no ongoing security threat. Our operations were not impacted by this incident and have continued safely and securely.” Heights said its internal systems and operations were not affected, the platform has been secured, and there is no ongoing threat. The compromised customer information included contact details, financial and bank account data, government IDs and dates of birth. The affected data varies by person and may involve Heights Finance customers, loan applicants, people who inquired about its products, or former borrowers of Curo Management and related brands. Heights Finance is offering affected individuals 24 months of free credit monitoring and identity protection. The company said dark web monitoring has found no evidence that the stolen data has been published. No threat actor has claimed responsibility, and no known ransomware or extortion group has been linked to the breach so far. Follow me on Twitter: @securityaffairs and Facebook and Mastodon Pierluigi Paganini (SecurityAffairs – hacking, Heights Finance)
A custom Java web shell likely linked to the Clop ransomware gang was designed specifically for PTC Windchill and FlexPLM servers, with built-in features to decrypt credentials, enumerate file repositories, and steal files. Cybersecurity company ReliaQuest analyzed the web shell after it is believed to have been deployed in recent data theft attacks exploiting CVE-2026-12569, a critical remote code execution vulnerability affecting PTC Windchill. ReliaQuest says the implant is not a generic web shell repurposed for the attacks, but was instead built with detailed knowledge of Windchill's internal APIs, database schema, keystore, and file-vault structure. "This appears to be an application-specific evolution of Clop's established mass-exploitation playbook," ReliaQuest said in a report shared with BleepingComputer.
Microsoft has started testing a faster File Explorer and a less cluttered and more customizable context menu in Windows 11 preview builds rolling out to Insiders this week. As the File Explorer team explained in a Monday blog post, the changes focus on improving File Explorer speed, performance, and reliability and addressing customer-reported issues. The redesigned context menu experience also aims to make it faster, reduce clutter, and make it more customizable than ever before. At the bottom of the new right-click menu, Microsoft also added a "Customize menu" shortcut to the Settings page, where users can tweak the context menu to suit their preferences. "We've continued refining File Explorer based on that feedback, removing friction and improving the details that help make everyday tasks feel more natural and predictable. For example, file renames no longer get interrupted by background file synchronization, and case-only filename changes now appear immediately," Microsoft said.
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has confirmed that ransomware gangs are also exploiting a high-severity Windows Task Host vulnerability that was flagged as actively exploited in April. Task Host is a core Windows system component that allows DLL-based processes to run in the background and prevents data corruption by ensuring they close properly during shutdown. Tracked as CVE-2025-60710, this Windows privilege escalation security flaw was patched by Microsoft in November 2025 and stems from a link following weakness that affects Windows 11 and Windows Server 2025 devices. Following successful exploitation, local attackers with basic user permissions can gain SYSTEM privileges and take full control of unpatched devices. While it didn't share any details regarding ongoing attacks and Microsoft has yet to update its security advisory to confirm in-the-wild exploitation, CISA added CVE-2025-60710 to its list of actively exploited vulnerabilities on April 13 and gave Federal Civilian Executive Branch (FCEB) agencies two weeks to secure their systems.
Two critical vulnerabilities impacting MLflow, an open-source artificial intelligence (AI) platform, and FUXA, an open-source, web-based SCADA / HMI software built for operational technology (OT) and industrial automation, are witnessing malicious scanning and exploitation efforts. According to independent reports from watchTowr and VulnCheck, the vulnerabilities in question are as follows -
A ransomware affiliate calling itself Ransom Busters has been spotted proactively sending emails to victim organizations and claims to delete stolen data from ransomware groups' servers in exchange for a fee ranging from $20,000 to $60,000. "In these messages, the third-party offers to help the victim recover from ransomware attack. This immediately stands out as anomalous," GuidePoint Research
A threat actor is selling employee databases allegedly stolen from the Microsoft Azure infrastructure of multiple Fortune 500 companies after gaining access using compromised credentials. Starting July 31st, multiple posts from someone using the alias “TheHatman” advertised data dumps from major organizations, including McDonald's, Gap Inc., Vodafone, Tata Consultancy Services, HCL Technologies, InterContinental Hotels (IHG), and Kyndryl. In total, the threat actor claims to have 3.64 million data records, with the most recent breach posted on Sunday, containing an alleged 1.7 million employee records from McDonalds. “I’m selling McDonald’s Corporation internal employee dump downloaded directly from Azure Tenant using compromised credentials,” the threat actor says in the post.
The SANDCLOCK LiteLLM supply-chain attack exposed credentials across 2,038 repositories, affecting technology, finance, healthcare, retail and more. Resecurity (USA) estimated the most affected sectors by the “SANDCLOCK” backdoor, which was planted as a result of the code repository compromise. According to cybersecurity experts, LiteLLM / TeamPCP Supply-Chain Attack will have long-lasting consequences. By compromising a well-known component in AI applications, adversaries will multiply the blast radius—some of the victim organizations are still unaware of the backdoor and its impact. LiteLLM is a popular open-soure AI gateway and utility library that unifies API calls for over 100 large language model providers, such as OpenAI, Anthropic, Google Gemini, and local Ollama models. Such incidents involve substantial MTTD (Mean Time to Detect) and MTTR (Mean Time to Respond). The threat actor group “TeamPCP” compromised maintainer credentials for LiteLLM and published malicious package versions 1.82.7 and 1.82.8 to PyPI around March 2026 – creating a window of exposure lasting at least a few months. Over 2,500+ organizations and hundreds of thousands of CI/CD environments suffered full-credential exposure, compromising cloud infrastructure keys, repository access tokens, SSH credentials, Kubernetes secrets, and AI provider API keys (such as OpenAI and Anthropic). Resecurity has acquired the 150GB archive attributed to the LiteLLM supply-chain attack conducted by TeamPCP using the “SANDCLOCK” credential-stealer. Per published incident reporting — accompanying victim manifests enumerate 898 compromised GitHub owners (organisations/accounts) across 2,038 repositories. The affected owners include major global enterprises — among them Microsoft, Azure, IBM, NVIDIA, PayPal (Zettle), Deloitte, Bosch, S&P Global, Elevance Health, 84.51° (Kroger), Adeo (Leroy Merlin), Kärcher, Dräger, ID.me and 1inch. Top 10 the most impacted sectors (by victim organization profile): Technology / Software Banking / Finance / Insurance Healthcare / Pharma / Medtech Retail / E-Commerce Media / Gaming / Adtech Manufacturing / Industrial Professional Services Cybersecurity Crypto Government Resecurity enumerated 2,146 records by key name (values never inspected beyond structural masking). The composition is overwhelmingly GitHub CI-CD identity material, with a long tail of high-value cloud and registry credentials. Victim manifests (owners.txt, repos.txt) enumerate 898 distinct compromised GitHub owners across 2,038 repositories. The distribution is long-tailed: 631 owners have a single affected repo, while the most-affected owner (Cencosud-Cencommerce) has 64. Critically, the owner list includes major global enterprises and regulated organisations. Every organization affected by the LiteLLM incident should revoke or rotate GitHub App private keys, PATs, AWS/GCP/Firebase credentials, ECR/JFrog tokens, SSH keys, and signing passwords, and invalidate sessions. Follow me on Twitter: @securityaffairs and Facebook and Mastodon Pierluigi Paganini (SecurityAffairs – hacking, newsletter)
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