Hackers Spied on a Stock Exchange Executive's Outlook Mailbox for Five Months

Summary: Symantec and Carbon Black's Threat Hunter Team reported that unknown attackers spent at least five months inside the Outlook mailbox of a senior executive at a major global stock exchange, copying it in small batches through Dropbox and OneDrive. First malicious activity appeared on October 10, 2025, with two binaries already running as SYSTEM, and the mailbox stealer - built on the Aspose .NET library - ran eight more times through February 17, 2026, with the last observed activity on March 19, 2026.
Key Takeaway: Five months of quiet access to one executive's inbox can expose non-public listing details, enforcement matters, and market-moving plans, and with no CVE and no attribution, no patch closes this gap.

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