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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT Security Bulletin ASB-2019.0272.2 Microsoft Internet Explorer memory corruption vulnerability 24 September 2019 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Internet Explorer 9 Internet Explorer 11 Operating System: Windows Impact/Access: Execute Arbitrary Code/Commands -- Remote with User Interaction Resolution: Patch/Upgrade CVE Names: CVE-2019-1367 Member content until: Thursday, October 24 2019 Revision History: September 24 2019: Microsoft advise that the vulnerability is being exploited in the wild. September 24 2019: Initial Release OVERVIEW Microsoft has released a security update for Internet Explorer versions 9 and 11 to address a memory corruption vulnerability. [1] It is being exploited in the wild. [1] [2] IMPACT "A remote code execution vulnerability exists in the way that the scripting engine handles objects in memory in Internet Explorer. The vulnerability could corrupt memory in such a way that an attacker could execute arbitrary code in the context of the current user. An attacker who successfully exploited the vulnerability could gain the same user rights as the current user. If the current user is logged on with administrative user rights, an attacker who successfully exploited the vulnerability could take control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. In a web-based attack scenario, an attacker could host a specially crafted website that is designed to exploit the vulnerability through Internet Explorer and then convince a user to view the website, for example, by sending an email." [1] MITIGATION Microsoft has published security updates for all platforms. [1] There are also workarounds available for administrators unable to install these updates yet: "Restrict access to JScript.dll For 32-bit systems, enter the following command at an administrative command prompt: takeown /f %windir%\system32\jscript.dll cacls %windir%\system32\jscript.dll /E /P everyone:N For 64-bit systems, enter the following command at an administrative command prompt: takeown /f %windir%\syswow64\jscript.dll cacls %windir%\syswow64\jscript.dll /E /P everyone:N takeown /f %windir%\system32\jscript.dll cacls %windir%\system32\jscript.dll /E /P everyone:N Impact of Workaround Implementing these steps might result in reduced functionality for components or features that rely on jscript.dll. To be fully protected, Microsoft recommends the update be installed as soon as possible. Please revert the mitigation steps before installing the update to return to a full state. By default, IE11, IE10, and IE9 uses Jscript9.dll which is not impacted by this vulnerability. This vulnerability only affects certain websites that utilize jscript as the scripting engine. How to undo the workaround For 32-bit systems, enter the following command at an administrative command prompt: cacls %windir%\system32\jscript.dll /E /R everyone For 64-bit systems, enter the following command at an administrative command prompt: cacls %windir%\system32\jscript.dll /E /R everyone cacls %windir%\syswow64\jscript.dll /E /R everyone" [1] REFERENCES [1] CVE-2019-1367 | Scripting Engine Memory Corruption Vulnerability https://portal.msrc.microsoft.com/en-us/security-guidance/advisory/CVE-2019-1367 [2] Microsoft releases out-of-band security update to fix IE zero-day & Defender bug https://www.zdnet.com/article/microsoft-releases-out-of-band-security-update-to-fix-ie-zero-day-defender-bug/ AusCERT has made every effort to ensure that the information contained in this document is accurate. However, the decision to use the information described is the responsibility of each user or organisation. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQIVAwUBXYlabGaOgq3Tt24GAQiFCA//fCa9rtGgDP5d22GjHbppTlLwpF2cm9cU y//cEoXennhbO1FZFxj9aGbq+uY4W+6niK438XyJRceVtWedYrwZoiHpvw/MJXNc hMe29+uxSO/5PCjUWiAX3J+I2N5RJGu9UiQOPQRrCF3oJOkfI0MBcbWJss28a1Qh 3zI6HpaZYs5UTOQ9PSRBrl4P9EJrcigIHXFMZ9Cqq9mFX9Zg81oI5URTcUntVJHP M/MqEtwAJDjlX1dfXA6k0ByErf+wWO97ZK5DzpxJyrcmw8/UQRB20u2t6j97aspR +2NkeHw4sjF3LSeXGjbrv44MzUsxu+RIkPTkIedHrdoiJ/o9xlB4PrVjJ0bc7uJf nR3vE+CoHWds3+dx39b42feMXcB9O5V84cHmOI4ZTAcvXJOO0VviCwoXsncO3HJM ktOCE+6wJe5aA+279VUN6K8C8oV0QN7FsSOgakuZhDrZOwnJstFILg8rC28wPV6q bQPqZ0u/f0Os8R0Co/8BhfBUaaZ2eWfDF5TaoBkNOEArBp6g8DoEs370HyUqUypp kQF6B2PgqEai582rC3g5VhkVtxmcbPFLxsybcKUVyVH2EwnUx8Qu2QeBcQOKIdtl E3FGGTsxjgXROlftQ8eqU89abGoqIk49rTLNMkyyo8uoU+g+9OcBKC/DVyJOAJOR ChSLv0h4GOw= =T1dD -----END PGP SIGNATURE-----