Last updated: August 19, 2026 at 1:47 AM UTC
All 741 Vulnerability 286 Breach 129 Threat 319 Defense 7
Tag: screen-sharing (2 articles)Clear

Exploited macOS Screen Sharing flaw gives attackers root to plant miners

The Netherlands cyber agency warned that attackers are exploiting a recently patched macOS flaw to gain root on internet-exposed Macs and install cryptocurrency miners. Tracked as CVE-2026-65400 and scored 9.8, the authentication flaw in the Screen Sharing component lets a network attacker authenticate to the built-in remote desktop service, which uses VNC on port 5900, without valid credentials due to flawed state management. Apple fixed it in emergency updates on August 6 for macOS Tahoe, Sequoia, and Sonoma. Screen Sharing is off by default, but any Mac with it enabled and reachable from the internet is at high risk, and several have already been compromised to run Monero miners.

Check
Install Apple's August macOS updates on all Macs, and confirm Screen Sharing is disabled or that port 5900 is not reachable from the internet on any system where remote desktop is enabled.
Affected
Macs with Screen Sharing enabled and reachable from the internet on unpatched macOS Tahoe, Sequoia, or Sonoma (CVE-2026-65400); a network attacker can authenticate without credentials and gain root.
Fix
Update macOS, disable Screen Sharing where it is not needed, restrict remote desktop access to trusted networks or a VPN, and check exposed Macs for unauthorized access and cryptominer processes.

Iranian hackers used Microsoft Teams chat to social-engineer victims, then dressed up their espionage as a Chaos ransomware attack to throw off blame

Rapid7 disclosed an Iranian state-sponsored intrusion that disguised itself as a Chaos ransomware attack to mask the real goal: cyber-espionage. The threat actor (assessed with moderate confidence as MuddyWater, linked to Iran's Ministry of Intelligence and Security) initiated chat requests through Microsoft Teams, walked employees into screen-sharing sessions, then captured credentials and manipulated MFA prompts. Some victims were asked to type their passwords into local text files during the call. Persistence came from a custom backdoor (Game.exe) deployed alongside DWAgent, AnyDesk, and RDP. The fake ransomware note and Chaos leak-portal entry concealed the espionage.

Check
Search Microsoft Teams logs for external chat invitations from unknown Entra tenants since January. Hunt endpoints for DWAgent, AnyDesk, ms_upd.exe, or Game.exe processes installed without IT approval.
Affected
Organizations allowing external Microsoft Teams chats by default - the campaign starts with chat invitations from attacker-controlled tenants. Acute risk for sectors MuddyWater historically targets: government, defense, telecoms, energy, and Israeli organizations. The 'IT Support' impersonation pattern works against any helpdesk-heavy enterprise. Iranian APT activity has been increasing through early 2026.
Fix
Restrict external Microsoft Teams chat to allowlisted partner tenants only. Block external screen-sharing requests by default. Brief staff that real IT support never asks them to type passwords into local files or read out MFA codes during a Teams call. Block Rapid7's published Stagecomp/Darkcomp code-signing certificate at the EDR layer.