Home / Tech / News / Hackers exploited Word flaw for months while Microsoft investigated

Hackers exploited Word flaw for months while Microsoft investigated

(AFP file photo)

Google’s security researchers, for example, give vendors just 90 days’ warning before publishing flaws they find. Microsoft Corporation declined to say how long it usually takes to patch a flaw.

To understand why it is so difficult to defend computers from even moderately capable hackers, consider the case of the security flaw officially known as CVE-2017-0199.

The bug was unusually dangerous but of a common genre: it was in Microsoft software, could allow a hacker to seize control of a personal computer with little trace, and was fixed April 11 in Microsoft's regular monthly security update.

But it had travelled a rocky, nine-month journey from discovery to resolution, which cyber security experts say is an unusually long time.

Google's security researchers, for example, give vendors just 90 days' warning before publishing flaws they find. Microsoft Corporation declined to say how long it usually takes to patch a flaw.

While Microsoft investigated, hackers found the flaw and manipulated the software to spy on unknown Russian speakers, possibly in Ukraine.

And a group of thieves used it to bolster their efforts to steal from millions of online bank accounts in Australia and other countries.

Those conclusions and other details emerged from interviews with researchers at cyber security firms who studied the events and analysed versions of the attack code.

Microsoft confirmed the sequence of events.

The tale began last July, when Ryan Hanson, a 2010 Idaho State University graduate and consultant at boutique security firm Optiv Inc in Boise, found a weakness in the way that Microsoft Word processes documents from another format. That allowed him to insert a link to a malicious programme that would take control of a computer.

Combining flaws

Hanson spent some months combining his find with other flaws to make it more deadly, he said on Twitter. Then in October he told Microsoft. The company often pays a modest bounty of a few thousands dollars for the identification of security risks.

Soon after that point six months ago, Microsoft could have fixed the problem, the company acknowledged. But it was not that simple. A quick change in the settings on Word by customers would do the trick, but if Microsoft notified customers about the bug and the recommended changes, it would also be telling hackers about how to break in.

Alternatively, Microsoft could have created a patch that would be distributed as part of its monthly software updates. But the company did not patch immediately and instead dug deeper. It was not aware that anyone was using Hanson's method, and it wanted to be sure it had a comprehensive solution.


"We performed an investigation to identify other potentially similar methods and ensure that our fix addresses [sic] more than just the issue reported," Microsoft said through a spokesman, who answered emailed questions on the condition of anonymity. "This was a complex investigation."

Hanson declined interview requests.

The saga shows that Microsoft's progress on security issues, as well as that of the software industry as a whole, remains uneven in an era when the stakes are growing dramatically.

The United States has accused Russia of hacking political party emails to interfere in the 2016 presidential election, a charge Russia denies, while shadowy hacker groups opposed to the U.S. government have been publishing hacking tools used by the Central Intelligence Agency and National Security Agency.

Attacks begin

 It is unclear how the unknown hackers initially found Hanson's bug. It could have been through simultaneous discovery, a leak in the patching process, or even hacking against Optiv or Microsoft.

In January, as Microsoft worked on a solution, the attacks began.

The first known victims were sent emails enticing them to click on a link to documents in Russian about military issues in Russia and areas held by Russian-backed rebels in eastern Ukraine, researchers said. Their computers were then infected with eavesdropping software made by Gamma Group, a private company that sells to agencies of many governments.

The best guess of cyber security experts is that one of Gamma's customers was trying to get inside the computers of soldiers or political figures in Ukraine or Russia; either of those countries, or any of their neighbours or allies, could have been responsible. Such government espionage is routine.

The initial attacks were carefully aimed at a small number of targets and so stayed below the radar. But in March, security researchers at FireEye Inc noticed that a notorious piece of financial hacking software known as Latenbot was being distributed using the same Microsoft bug.

FireEye probed further, found the earlier Russian-language attacks, and warned Microsoft. The company, which confirmed it was first warned of active attacks in March, got on track for an April 11 patch.

Then, what counts as disaster in the world of bug-fixers struck. Another security firm, McAfee, saw some attacks using the Microsoft Word flaw on April 6.

After what it described as "quick but in-depth research," it established that the flaw had not been patched, contacted Microsoft, and then blogged about its discovery on April 7.

The blog post contained enough detail that other hackers could mimic the attacks.

Other software security professionals were aghast that McAfee did not wait, as Optiv and FireEye were doing, until the patch came out.

McAfee Vice President Vincent Weafer blamed "a glitch in our communications with our partner Microsoft" for the timing. He did not elaborate.

Follow HT Tech for the latest tech news and reviews, also keep up with us on Twitter, Facebook, and Instagram. For our latest videos, subscribe to our YouTube channel.