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A Russian state-supported espionage group spent months reading Western mailboxes through a then-unknown flaw in Zimbra's webmail client. The payload goes after the last 90 days of email, the organization's entire email directory, the password saved in the browser and the codes kept for two-factor recovery. Opening the message was enough to start it. The NSA , CISA and partner agencies published a joint advisory on the campaign Thursday, alongside research from Palo Alto Networks' Unit 42 and Proofpoint. The advisory calls the technique "a view-based exploit that only requires a user to view a malicious email" in a vulnerable client. It says the actors have been targeting and compromising Western government and commercial organizations through Zimbra since at least July 2025. The flaw, CVE-2025-66376 , is a stored cross-site scripting vulnerability in Zimbra's Classic UI. A crafted HTML email abuses CSS @import handling to execute JavaScript inside a...

Most of this week's trouble came dressed as something useful. A package stole data. A fake extension opened remote access. A safety app became spyware. An image gave hidden orders to an AI agent. Other threats hid in open systems, weak code, and normal network traffic. The threats change every week. Subscribe, and we’ll alert you when each new ThreatsDay Bulletin is out. The danger was easy to miss because it looked ordinary. Here is the full list:

Cybersecurity researchers have uncovered a sandbox escape vulnerability in Anthropic's Claude Cowork that makes it possible to break out of the confines of a Linux virtual machine (VM) within which the agent runs to read or write files anywhere on the Mac. Accomplish AI, which shared details of the vulnerability with The Hacker News ahead of publication, said about 500,000 macOS users running local Cowork sessions were affected prior to it being patched. It has been codenamed SharedRoot . "We connected a folder to a fresh Claude Cowork session, sent one short message, and watched the agent escape the sandbox," Oren Yomtov, principal security researcher at Accomplish AI, said . "From inside the VM, it reached the host Mac and read and wrote files all over it, far outside the folder we'd connected, with no permission prompt anywhere." With this level of access, the agent can access any data stored on the Mac via the user's account, including SSH ke...

The Chaos ransomware group ran its command-and-control through the victim's own browser. Cisco Talos on Thursday detailed msaRAT , the Rust implant behind it, found on a compromised Windows machine ahead of the encryptor. The implant never opens an outbound connection of its own. Its process talks to 127.0.0.1 and nothing else. It starts Chrome or Edge in headless mode and drives the browser over the Chrome DevTools Protocol, the browser's own debugging API. Every C2 message travels out from there through a WebRTC data channel relayed by Twilio's TURN service, so what a defender sees on the wire is a browser calling Cloudflare and Twilio. The attacker's own server address never appears at all. Chrome Does the Talking msaRAT looks for Chrome or Edge through environment variables first, then falls back to the registry for Chrome. If no matching browser is found, the CDP path is skipped. When it finds one, it starts the browser without a visible window using -...

An exposed Alibaba Cloud server has revealed a China-nexus operation that Group-IB tracks as JadeProx . The cluster has targeted government, healthcare, and education organizations across Asia and Latin America with a previously undocumented Windows loader called TriBack Loader. Group-IB found the server in mid-April 2026 in Alibaba Cloud's Singapore region; it was offline by the time the report published on July 23, 2026. Its bash history, phishing packages, post-exploitation tools, and webshell paths laid the operation out: active intrusions against a Vietnamese public hospital's medical imaging system and Malaysia's Ministry of Foreign Affairs, scanning and exploitation follow-up against Hong Kong education infrastructure, and a spear-phishing package addressed to the National Congress of Honduras. The operators reached the hospital's imaging server through webshells planted on an exposed Java management interface. One Loader, Four Builds TriBack Loader a...