All news with #rhysida tag

🔒 Microsoft says it disrupted a malware-signing-as-a-service operation, codenamed OpFauxSign, that abused Artifact Signing to produce short-lived fraudulent code-signing certificates and deliver signed malware. The company seized the SignSpace site signspace[.]cloud, took hundreds of virtual machines offline, and blocked hosting for the underlying code. Operators tied to the group, called Fox Tempest, sold signing services for $5,000–$9,000 and facilitated distribution of Rhysida ransomware and loaders like Oyster. Microsoft added the actor likely used stolen U.S. and Canadian identities to pass verification and repeatedly adapted its tradecraft as defenders revoked certificates.

🔒 Cookeville Regional Medical Center has notified 337,917 patients that personal and medical data were accessed during a July 11–14, 2025 intrusion tied to the ransomware group Rhysida. The hospital began mailing breach letters in April 2026, roughly nine months after detection, and said files may include Social Security numbers, driver’s license data, treatment and insurance information. Rhysida claimed the attack in August 2025 and posted sample files; it demanded 10 Bitcoin. CRMC is offering 12 months of identity protection through Experian and reports additional security measures are in place.

🔒Rhysida, a known enterprise-focused ransomware gang, is distributing malware via malvertising on Microsoft's Bing that redirects users to fake download pages for common tools such as Microsoft Teams, PuTTY, and Zoom. Victims who download receive an initial access trojan called OysterLoader, which establishes a persistent backdoor and is signed with Microsoft-like certificates to appear legitimate. The campaign pairs obfuscation/packing to lower static detection with trusted code signing to bypass allow-lists and AV. Experts urge behavior-based EDR, certificate pinning, DNS filtering, and tighter certificate oversight.

🛡️ Rhysida ransomware operators have shifted to malvertising and the abuse of Microsoft Trusted Signing certificates to slip malware past defenses. By buying Bing search ads that point to convincing fake download pages for Microsoft Teams, PuTTY and Zoom, they deliver initial access tools such as OysterLoader (formerly Broomstick/CleanUpLoader) and Latrodectus. Signed, packaged binaries evade static detection and often run without scrutiny on Windows endpoints.

🔒 On October 17, the ransomware group Rhysida posted the German machine manufacturer Geiger on a darknet victims list, claiming to offer data stolen from the company. The attackers set an asking price of 10 BTC (roughly €1 million) and indicated a sale deadline of October 24, 2025, without specifying the scope or types of data. Geiger has not publicly responded to the claim. Security researchers characterize Rhysida as financially motivated and likely operating from Russia or the CIS.

🔒 Microsoft Threat Intelligence has revoked more than 200 code-signing certificates that were fraudulently used to sign counterfeit Microsoft Teams installers delivering a persistent backdoor and ransomware. The campaign, tracked as Vanilla Tempest (also known as Vice Spider/Vice Society), employed SEO poisoning and malvertising to lure users to spoofed download sites hosting fake MSTeamsSetup.exe files that deployed the Oyster backdoor and ultimately Rhysida ransomware. Microsoft says the actor abused Trusted Signing and services such as SSL.com, DigiCert and GlobalSign to sign malicious binaries. A fully enabled Microsoft Defender Antivirus detects and blocks these threats, and Microsoft provides guidance through Microsoft Defender for Endpoint for mitigation and investigation.

🔒 Microsoft disclosed it revoked more than 200 certificates after a threat actor tracked as Vanilla Tempest used them to fraudulently sign malicious binaries, including fake Microsoft Teams installers that delivered the Oyster backdoor and led to Rhysida ransomware deployments. The activity was detected in late September 2025 and disrupted earlier this month, and Microsoft has updated security solutions to flag the associated signatures. The actor abused SEO poisoning and bogus download domains impersonating Teams to distribute trojanized installers. Users are advised to download software only from verified sources and to avoid suspicious links or ads.

🔒 Microsoft disrupted a campaign by the financially motivated group Vanilla Tempest (also tracked as VICE SPIDER/Vice Society) after revoking over 200 code signing certificates used to sign malicious Microsoft Teams installers. The attackers used malvertising and SEO-poisoned domains mimicking Teams to distribute fake MSTeamsSetup.exe files that deployed the Oyster backdoor. The intervention curtailed a wave of Rhysida ransomware launches.