0patch has issued an unofficial fix for an actively exploited Microsoft Windows zero-day vulnerability that could enable malformed signature-approved files to evade Mark-of-the-Web security measures, according to The Hacker News.
Such a patch follows HP Wolf Security's discovery of a Magniber ransomware campaign leveraging phony security updates that include a JavaScript file that has the MotW tag, which facilitates arbitrary execution without the SmartScreen warning. Exceptions returned by SmartScreen during malformed signature parsing cause the zero-day, said 0patch co-founder Mitja Kolsek.
"Attackers therefore understandably prefer their malicious files not being marked with MotW; this vulnerability allows them to create a ZIP archive such that extracted malicious files will not be marked," said Kolsek.
Unofficial patches have also been issued earlier by 0patch for a separate zero-day MotW bypass vulnerability discovered by security researcher Will Dormann, which involved Windows' failure to provide the MotW identifier to specially crafted .ZIP file-extracted files.
Included in the exposed dataset labeled "PDL" were individuals' full names, email addresses, phone numbers, location data, professional summaries, and skills, as well as education and employment histories.
Attackers could leverage the issue — which impacts Nexus 3000, 7000, and 9000 series switches with vulnerable NX-OS versions with DHCPv6 activated and are in standalone NX-OS mode — to facilitate continuous crashes of the dhcp_snoop process and a denial-of-service condition.
Higher rewards of up to $250,000 will be given by Google for the discovery of memory corruption flaws in the Chrome browser shown to achieve remote code execution using a non-sandboxed process as part of a more robust vulnerability reward program.