Experts believe that the Windows kernel zero-day vulnerability fixed this week by Microsoft with its Patch Tuesday updates has been exploited by several threat actors, including a new group.
The actively exploited vulnerability, tracked as CVE-2018-8611, has been described by Microsoft as a privilege escalation issue related to the failure of the Windows kernel to properly handle objects in memory.
The flaw was reported to Microsoft by researchers at Kaspersky Lab. This was the third month in a row Microsoft patched a Windows zero-day reported by the cybersecurity firm – in October it fixed CVE-2018-8453, which had been exploited by FruityArmor, and in November it resolved CVE-2018-8589, which had been used by multiple threat groups in attacks mostly aimed at the Middle East.
Kaspersky has described CVE-2018-8611 as a race condition in the Kernel Transaction Manager. The company says the vulnerability can be used not only to escalate privileges, but also to escape the sandbox of the Chrome and Edge web browsers.
“This vulnerability successfully bypasses modern process mitigation policies, such as Win32k System call Filtering that is used, among others, in the Microsoft Edge Sandbox and the Win32k Lockdown Policy employed in the Google Chrome Sandbox. Combined with a compromised renderer process, for example, this vulnerability can lead to a full Remote Command Execution exploit chain in the latest state-of-the-art web-browsers,” Kaspersky explained.
The security firm says it has found several builds of an exploit for this vulnerability, including one adapted for the latest versions of Windows.
Kaspersky says multiple threat actors appear to have exploited the flaw, including FruityArmor and a recently discovered group tracked by the company as SandCat.
SandCat has been observed using FinFisher/FinSpy spyware and CHAINSHOT, a piece of malware analyzed earlier this year by Palo Alto Networks after it had been spotted in Middle East attacks involving a Flash Player zero-day (CVE-2018-5002).
According to Kaspersky, the latest Window zero-day was used in attacks aimed at entities in the Middle East and Africa. Some connections have been found to the vulnerability patched by Microsoft in October – CVE-2018-8589 was dubbed “Alice” by malware developers, while CVE-2018-8611 was referred to as “Jasmine.”
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