(Adds comment from researchers who discovered flaw, possible methods for leaks)
By Raphael Satter, Christopher Bing and Joseph Menn
WASHINGTON, March 10 (Reuters) – At least 10 different hacking groups are using recently discovered flaws in Microsoft Corp’s mail server software to break in to targets around the world, cybersecurity company ESET said in a blog post on Wednesday.
The breadth of the exploitation adds to the urgency of the warnings being issued by authorities in the United States and Europe about the weaknesses found in Microsoft’s Exchange software.
The security holes in the widely used mail and calendaring solution leave the door open to industrial-scale cyber espionage, allowing malicious actors to steal emails virtually at will from vulnerable servers or move elsewhere in the network. Tens of thousands of organizations have already been compromised, Reuters reported last week, and new victims are being made public daily.
Earlier on Wednesday, for example, Norway’s parliament announced data had been “extracted” in a breach linked to the Microsoft flaws. Germany’s cybersecurity watchdog agency also said on Wednesday two federal authorities had been affected by the hack, although it declined to identify them.
While Microsoft has issued fixes, the sluggish pace of many customers’ updates – which experts attribute in part to the complexity of Exchange’s architecture – means the field remains at least partially open to hackers of all stripes. The patches do not remove any back door access that has already been left on the machines.
In addition, some of the back doors left on compromised machines have passwords that are easily guessed, so that newcomers can take them over.
Microsoft declined comment on the pace of customers’ updates. In previous announcements pertaining to the flaws, the company has emphasized the importance of “patching all affected systems immediately.”
Although the hacking has appeared to be focused on cyber espionage, experts are concerned about the prospect of ransom-seeking cybercriminals taking advantage of the flaws because it could lead to widespread disruption.
ESET’s blog post said there were already signs of cybercriminal exploitation,…