When used in synergy, two recently discovered Windows flaws allow threat actors to run malware on a target endpoint (opens in new tab), researchers have found.
The two flaws are a Windows Search zero-day, and a Microsoft Office OLEObject flaw.
Through the use of a weaponized Word document, the Search zero-day can be used to automatically open a search window with a remotely hosted malware. This was made possible due to how Windows handles a URI protocol handler called “search-ms”.
OLEObject flaw
This protocol allows apps and HTML links to launch customized searches. The problem is that Windows will warn the victim that the site is trying to open Windows Explorer, possibly alerting most of them that something’s amiss.
However, Hacker House co-founder and security researcher Matthew Hickey discovered that by pairing this flaw with the Microsoft Office OLEObject flaw, a search window can be opened simply by opening a Word document.
Long story short, a crook can land a weaponized Word document via a phishing email, and once the victim opens it, a custom Windows Search page can pop up, containing malware hosted remotely.
The share can carry any name the attacker wants, BleepingComputer has warned, including things like “Critical Updates”.
Luckily enough, there’s a way to mitigate the threat, by deleting the search-ms protocol handler from the Windows Registry. To do that, run CMD as Administrator, and then run this command: “reg delete HKEY_CLASSES_ROOT\search-ms /f”.
Abusing URI protocol handlers seems to be high fashion these days, as earlier this week, researchers found cybercrooks abusing such a flaw found in the Microsoft Windows Support Diagnostic Tool (MSDT). With the help of a weaponized Word document, the “ms-msdt” URI protocol handler can be launched which, in turn, can execute any PowerShell commands.
The flaw, dubbed “Follina”, was found being used by Chinese state-sponsored attackers, against the international Tibetan community.
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