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Microsoft Exchange Vulnerability CVE-2026-62911: What Administrators Should Do and How Zscaler Can Help
High-severity authentication bypass CVE-2026-62911 in Exchange Server has public exploit code; about 22,000 servers remain unpatched and internet-exposed.
Microsoft's August 2026 Patch Tuesday fixed CVE-2026-62911 (CVSS 8.0), an authentication bypass affecting Exchange Server 2016, 2019 and Subscription Edition. Successful exploitation lets an attacker with basic privileges take over all mailboxes on the targeted server, including reading and sending email and downloading attachments. As of September 1, Shadowserver identified roughly 22,000 unpatched, internet-exposed Exchange servers, including about 6,200 in the US and 5,100 in Germany. NCSC-NL confirmed working exploit code is publicly available, while CISA has not yet reported exploitation in the wild.
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Windows CLFS and five exploits used by ransomware operators (Exploit #2
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Operation RapidRust: APT36 Deploys RUSTYSHADE, RUSTYMOVE, PSNATCH, and BASHNATCH
Zscaler details Operation RapidRust: APT36 deploys four new tools including RUSTYSHADE, a Rust backdoor using private GitHub repos for encrypted C2.
Zscaler ThreatLabz documents Operation RapidRust, a campaign by Pakistan-aligned APT36 deploying four new tools: RUSTYSHADE, a 64-bit Rust Windows backdoor that uses attacker-controlled private GitHub repositories with a hardcoded PAT and AES-256-GCM-encrypted messages for C2; RUSTYMOVE; PSNATCH, a PowerShell file stealer that scans Office documents, archives, media, and databases modified in the last 120 days and exfiltrates up to 5 GB per run to per-machine GitHub repositories; and BASHNATCH. The backdoor was dropped via PowerShell from attacker-controlled Backblaze B2 storage and supports screenshots, webcam capture, file listing, downloads, and shell command execution.
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CaptiveCrunch: Midnight Blizzard Weaponizes Hotel Wi-Fi Captive Portals to Steal Microsoft 365 Credentials
Zscaler details CaptiveCrunch: Midnight Blizzard's Storm-2945 compromises hotel Wi-Fi captive portals to redirect guests and harvest Microsoft 365 credentials via device code phishing.
Zscaler ThreatLabz analyzed the CaptiveCrunch credential theft campaign first reported by Microsoft on July 31. Microsoft attributes the activity to Storm-2945, a sub-cluster of Russia-linked Midnight Blizzard (APT29, Cozy Bear, NOBELIUM, BlueBravo). The actor manipulates DNS and HTTP traffic on captive portal networks at hotels and conference centers, redirecting victims to attacker-controlled infrastructure for Microsoft 365 credential harvesting, device code phishing, and malware delivery. Evidence indicates shared captive portal services were compromised rather than each venue being breached individually.
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⚡ Weekly Recap: iPhone Spyware, Microsoft 0-Day, TokenBreak Hack, AI Data Leaks and More
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Week in review: Several companies affected by the Salesloft Drift breach, Sitecore 0-day vulnerability
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