Hackers target Windows users exploiting a Zero

ACS Commons version 4.9.2 (and earlier) suffers from a Reflected Cross-site Scripting (XSS) vulnerability in version-compare and page-compare due to invalid JCR characters that are not handled correctly. An attacker could potentially exploit this vulnerability to inject malicious JavaScript content into vulnerable form fields and execute it within the context of the victim's browser. Exploitation of this issue requires user interaction in order to be successful.

Adobe InDesign version 16.0 (and earlier) is affected by an Out-of-bounds Write vulnerability when parsing a crafted file. An unauthenticated attacker could leverage this vulnerability to achieve remote code execution in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.

CVE-2021-28550 is a use-after-free memory corruption flaw in Adobe Acrobat DC and Acrobat Reader DC that an unauthenticated attacker can trigger by getting a victim to open a malicious PDF file. Successful exploitation allows arbitrary code execution in the context of the current user, giving the attacker the privileges of that user on the affected machine. Anyone running Acrobat or Acrobat Reader DC at or below versions 2021.001.20150, 2020.001.30020, or 2017.011.30194 is affected. The flaw was exploited as a zero-day in targeted attacks — Microsoft reported it being chained with Windows zero-days by an Austrian company's operators — and it is listed in CISA's Known Exploited Vulnerabilities catalog as of November 3, 2021. CISA's required action is to apply vendor updates, and defenders should treat exploited, user-targeted PDF attacks as the primary risk.

Do: Upgrade Acrobat and Acrobat Reader DC to versions later than 2021.001.20150, 2020.001.30020, and 2017.011.30194 on the respective tracks, per Adobe's May 2021 update and the CISA KEV required action. Until patched, avoid opening PDFs from untrusted sources and consider email-gateway filtering or sandboxing of PDF attachments. Check endpoint inventory for the affected version ranges and prioritize systems of users who handle unsolicited documents.

Acrobat Reader DC versions versions 2021.001.20150 (and earlier), 2020.001.30020 (and earlier) and 2017.011.30194 (and earlier) are affected by a Heap-based Buffer Overflow vulnerability. An unauthenticated attacker could leverage this vulnerability to achieve arbitrary code execution in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.