Security Affairspublished Jan 18, 21:02 UTC (Jan 18, 2020)ingested Sep 10, 06:12 UTC@securityaffairs

Microsoft provides mitigation for actively exploited CVE-2020

criticalExploit / PoC exploited in the wildimportance 60CVE-2020-0674

Read the original

Tagscve-2020-0674 exploit

Vulnerabilities mentionedAll →

CVE	Vulnerability	CVSS	EPSS	Flags	Affected	Exposure	Published
CVE-2020-0674	Use-After-Free RCE in Microsoft Internet Explorer Scripting Engine CVE-2020-0674 is a use-after-free memory corruption flaw (CWE-416) in the way the Internet Explorer scripting engine handles objects in memory, distinct from a series of sibling scripting-engine RCEs fixed at the same time (CVE-2020-0673, 0710, 0711, 0712, 0713, 0767). Triggering it requires user interaction: an attacker must convince a user to view a specially crafted web page (for example via a phishing link or malicious web content) while it renders in Internet Explorer, and the mishandled memory then allows code execution under the high-complexity, network-reachable conditions reflected in the CVSS vector (AV:N/AC:H/UI:R). Successful exploitation gives the attacker remote code execution with the privileges of the logged-in user, so the practical risk is highest for users browsing with Internet Explorer on Windows, including IE 8 through IE 11 targeted by the public exploits. Exploitation is confirmed in the wild: Microsoft warned of the flaw as an unpatched zero-day being used in targeted attacks before its February 2020 Patch Tuesday fix, public PoC/exploit code is available (including a working exploit for IE 8-11), the Magnitude exploit kit referenced in coverage used it as a delivery vector, and CISA added it to the Known Exploited Vulnerabilities catalog on 2021-11-03 alongside a very high EPSS score (86.9% probability of exploitation in 30 days, 100th percentile). The required remediation is to apply the Microsoft security updates from February 2020 that address this CVE. Do: Apply the Microsoft February 2020 Patch Tuesday security updates that fix CVE-2020-0674 on all Windows endpoints and servers, prioritizing per the CISA KEV required action. Until patched, limit Internet Explorer use to trusted sites and consider Microsoft's suggested mitigations (such as restricting active scripting); note that third-party micropatches existed that emulated the vendor workaround without its usability side effects. After patching, verify IE11 remediation status across the estate and, where feasible, retire Internet Explorer usage entirely to reduce exposure to this recurring scripting-engine bug class.	7.5	87%	KEV PoC ×4	microsoft internet explorer	masshundreds of millions of Windows endpoints (IE 11 was bundled with every supported Windows release at disclosure)	Feb 11, 2020

CVE

Vulnerability

CVSS

EPSS

Flags

Affected

Exposure

Published

CVE-2020-0674

Use-After-Free RCE in Microsoft Internet Explorer Scripting Engine

CVE-2020-0674 is a use-after-free memory corruption flaw (CWE-416) in the way the Internet Explorer scripting engine handles objects in memory, distinct from a series of sibling scripting-engine RCEs fixed at the same time (CVE-2020-0673, 0710, 0711, 0712, 0713, 0767). Triggering it requires user interaction: an attacker must convince a user to view a specially crafted web page (for example via a phishing link or malicious web content) while it renders in Internet Explorer, and the mishandled memory then allows code execution under the high-complexity, network-reachable conditions reflected in the CVSS vector (AV:N/AC:H/UI:R). Successful exploitation gives the attacker remote code execution with the privileges of the logged-in user, so the practical risk is highest for users browsing with Internet Explorer on Windows, including IE 8 through IE 11 targeted by the public exploits. Exploitation is confirmed in the wild: Microsoft warned of the flaw as an unpatched zero-day being used in targeted attacks before its February 2020 Patch Tuesday fix, public PoC/exploit code is available (including a working exploit for IE 8-11), the Magnitude exploit kit referenced in coverage used it as a delivery vector, and CISA added it to the Known Exploited Vulnerabilities catalog on 2021-11-03 alongside a very high EPSS score (86.9% probability of exploitation in 30 days, 100th percentile). The required remediation is to apply the Microsoft security updates from February 2020 that address this CVE.

Do: Apply the Microsoft February 2020 Patch Tuesday security updates that fix CVE-2020-0674 on all Windows endpoints and servers, prioritizing per the CISA KEV required action. Until patched, limit Internet Explorer use to trusted sites and consider Microsoft's suggested mitigations (such as restricting active scripting); note that third-party micropatches existed that emulated the vendor workaround without its usability side effects. After patching, verify IE11 remediation status across the estate and, where feasible, retire Internet Explorer usage entirely to reduce exposure to this recurring scripting-engine bug class.

7.5

87%

KEV PoC ×4

microsoft internet explorer

masshundreds of millions of Windows endpoints (IE 11 was bundled with every supported Windows release at disclosure)

Feb 11, 2020

Full article470 words · extracted from securityaffairs.com · click to collapse

Microsoft published a security advisory to warn of an Internet Explorer (IE) zero-day vulnerability (CVE-2020-0674) that is currently being exploited in the wild.

Microsoft has published a security advisory (ADV200001) that includes mitigations for a zero-day remote code execution (RCE) vulnerability, tracked as CVE-2020-0674, affecting Internet Explorer.

The tech giant confirmed that the CVE-2020-0674 zero-day vulnerability has been actively exploited in the wild.

“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.” reads the advisory published by Microsoft. “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.”

An attacker could exploit the flaw to can gain the same user permissions as the user logged into the compromised Windows device. If the user is logged on with administrative permissions, the attacker can exploit the flaw to take full control of the system.

The CVE-2020-0674 flaw could be triggered by tricking victims into visiting a website hosting a specially crafted content designed to exploit the issue through Internet Explorer.

Microsoft announced that it is currently working on a patch to address the vulnerability, the company will likely release an out-of-band update because attackers are already exploiting the flaw in the wild.

Microsoft suggests restricting access to JScript.dll using the following workaround to mitigate this zero-day flaw.

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

The company warns that implementing these mitigation might impact the functionality for components or features that use the jscript.dll.

“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.” continues the advisory.

To undo the workaround, use the following procedures.

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

[adrotate banner=”9″]

[adrotate banner=”12″]

Pierluigi Paganini

(SecurityAffairs – CVE-2020-0674, hacking)

[adrotate banner=”5″]

[adrotate banner=”13″]

Text extracted automatically; images, tables and formatting may be missing. Original: https://securityaffairs.com/96560/hacking/cve-2020-0674-ie-0day.html