Advisory Details

September 14th, 2018

Microsoft Windows VBScript Class_Terminate MSXML3 Use-After-Free Remote Code Execution Vulnerability

CVE ID	CVE-2018-8420
CVSS SCORE	6.8, AV:N/AC:M/Au:N/C:P/I:P/A:P
AFFECTED VENDORS	Microsoft
AFFECTED PRODUCTS	Windows
VULNERABILITY DETAILS	This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Microsoft Windows VBScript. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the handling of Class_Terminate methods when used together with MSXML3. By performing actions in VBScript, an attacker can cause a pointer to be reused after it has been freed. An attacker can leverage this vulnerability to execute code in the context of the current process.
ADDITIONAL DETAILS	Microsoft has issued an update to correct this vulnerability. More details can be found at: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2018-8420
DISCLOSURE TIMELINE	2018-06-05 - Vulnerability reported to vendor 2018-09-14 - Coordinated public release of advisory 2018-09-14 - Advisory Updated
CREDIT	Simon Zuckerbraun of Trend Micro Zero Day Initiative

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