Security News
Network and IT admins have been dealing with ongoing Microsoft 365 issues this week, reporting that some end users cannot use Microsoft Outlook or other Microsoft 365 apps. The issues started Monday, with numerous admins contacting BleepingComputer to say that some of their users are experiencing disruptive issues in Microsoft Outlook, with the program not opening, freezing after opening, seeing delays in mail delivery, or errors saying there is no valid license associated with the user.
Microsoft is working to address a known issue affecting Outlook for Microsoft 365 customers, causing slow starts and freezes as if Offline Outlook Data Files are being synced right after launch. Users will see errors saying, "Cannot start Microsoft Outlook. Cannot open the Outlook window. The set of folders cannot be opened. The attempt to log on to Microsoft Exchange has failed."
"These attacks likely rely on access to multiple virtual private servers in conjunction with rented cloud infrastructure, open proxies, and DDoS tools," the tech giant said in a post on Friday.Redmond said it further observed the threat actor launching layer 7 DDoS attacks from multiple cloud services and open proxy infrastructures.
Microsoft has confirmed that recent outages to Azure, Outlook, and OneDrive web portals resulted from Layer 7 DDoS attacks against the company's services. The outages occurred at the beginning of June, with Outlook.com's web portal targeted on June 7th, OneDrive on June 8th, and the Microsoft Azure Portal on June 9th. Microsoft did not share at the time that they were suffering DDoS attacks but hinted that they were the cause, stating for some incidents that they were "Applying load balancing processes in order to mitigate the issue."
Outlook.com is suffering a series of outages today after being down multiple times yesterday, with hacktivists known as Anonymous Sudan claiming to perform DDoS attacks on the service. This outage follows two major outages yesterday, creating widespread disruptions for global Outlook users, preventing users worldwide from reliably accessing or sending email and using the mobile Outlook app.
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The malware enables the operators to take control of the victim's Gmail, Outlook, Hotmail, or Yahoo email accounts, steal email data and 2FA codes arriving in the inbox, and send phishing emails from the compromised accounts. The victim clicks on the hyperlink on the page and downloads a RAR archive that contains a batch file with a CMD extension, which downloads a PowerShell script that fetches trojan DLLs and a set of legitimate executables from the C2 server.
If a miscreant carefully crafted a mail with that sound path set to a remote SMB server, when Outlook fetched and processed the message, and automatically followed the path to the file server, it would hand over the user's Net-NTLMv2 hash in an attempt to log in. The patch from a couple of months ago made Outlook use the Windows function MapUrlToZone to inspect where a notification sound path was really pointing, and if it was out to the internet, it would be ignored and the default sound would play.
Microsoft fixed a security vulnerability this week that could be used by remote attackers to bypass recent patches for a critical Outlook zero-day security flaw abused in the wild. "All Windows versions are affected by the vulnerability. As a result, all Outlook client versions on Windows are exploitable," Barnea explained.
Among the vulnerabilities fixed by Microsoft on May 2023 Patch Tuesday is CVE-2023-29324, a bug in the Windows MSHTML platform that Microsoft rates as "Important." Akamai's research team and Ben Barnea, the researcher who's credited with finding the flaw, disagree with that assessment, because "The new vulnerability re-enables the exploitation of a critical vulnerability that was seen in the wild and used by APT operators."