Security Experts:

Microsoft Patches Two Privilege Escalation Flaws Exploited in Attacks

Microsoft’s Patch Tuesday updates for September 2019 fix 80 vulnerabilities, including two Windows flaws that have been exploited in attacks. [UPDATE BELOW]

The zero-day vulnerabilities are CVE-2019-1214 and CVE-2019-1215. The first affects the Windows Common Log File System (CLFS) and it allows an authenticated attacker with regular user privileges to escalate permissions to administrator. The security hole was reported to Microsoft by a researcher from the Qihoo 360 Vulcan Team, but no details appear to have been released about the attacks exploiting the vulnerability.

It’s worth noting that while all supported versions of Windows appear to be affected by this weakness, Microsoft says exploitation is unlikely against the latest versions of the operating system.

Microsoft has not credited anyone for the second zero-day it patched on Tuesday. CVE-2019-1215 has been described by the company as a vulnerability in Winsock (ws2ifsl.sys) that allows a locally authenticated attacker to execute code with elevated privileges.

Unlike CVE-2019-1214, Microsoft lists the risk of exploitation as “more likely” in the case of CVE-2019-1215 for both older and newer versions of Windows.

“Interestingly, [ws2ifsl.sys] has been targeted by malware in the past, with some references going back as far as 2007. Not surprising, since malware often targets low-level Windows services,” experts at the Zero Day Initiative (ZDI) explained in a blog post.

Microsoft’s latest round of patches also addresses two vulnerabilities that were publicly disclosed before fixes were made available. One of them affects the Windows Text Service Framework (TSF) and it allows privilege escalation, while the other is a Windows Secure Boot bypass issue that allows an attacker with physical access to a device to read protected kernel memory. For both these vulnerabilities, Microsoft believes the risk of exploitation is “less likely.”

Of the total number of security holes resolved this month, 17 have been classified as “critical.” They impact Windows, Edge, SharePoint, and Azure DevOps Server (ADO) and Team Foundation Server (TFS).

Adobe’s Patch Tuesday updates only resolve three vulnerabilities: two code execution bugs in Flash Player and a DLL hijacking flaw in Application Manager.

UPDATE. Microsoft's initial advisories incorrectly marked CVE-2019-1214 and CVE-2019-1215 as "exploited." The vulnerabilities have not been exploited in attacks and the company has updated its advisories.

Related: Microsoft Patches Over 90 Vulnerabilities With August 2019 Updates

Related: Buhtrap Group Used Windows Zero-Day in Government Attack

Related: Microsoft Patches Two Windows Flaws Exploited in Targeted Attack

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.