Microsoft Excel XLS File Use-After-Free Remote Code Execution Vulnerability

April 15th, 2020
ZDI-20-470 ZDI-CAN-10638

CVE ID

CVE-2020-0906

CVSS Score

7.8 AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected Vendors

Microsoft

Affected Products

Excel

Vulnerability Details

This vulnerability allows remote attackers to execute arbitrary code on affected installations of Microsoft Excel. 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 processing of XLS files. Crafted data in an XLS file 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-2020-0906

Disclosure Timeline

  • 2020-03-05 - Vulnerability reported to vendor
  • 2020-04-15 - Coordinated public release of advisory

Credit

hackyzh and lm0963 of DBAppSecurity Zion Lab

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