Zero-day vulnerability in Microsoft Excel

Memory corruption
CVE-2009-0238

Known malware:

TROJ_MDROPPER.XR (TrendMicro)
Exploit - MSExcel.r (McAfee)
Trojan.Mdropper.AC (Symantec)

Vulnerability details

Advisory: SB2009022301 - Remote code execution in Microsoft Excel

Vulnerable component: Microsoft Excel

CVE-ID: CVE-2009-0238

CVSSv3 score: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H/E:F/RL:O/RC:C

CWE-ID: CWE-119 - Memory corruption

Description:

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The weakness exists due to boundary error when parsing the Excel spreadsheet file format. A remote attacker can create a specially crafted Excel file containing a malformed object, trick the victim into opening it, trigger memory corruption and execute arbitrary code on the target system with privileges of the current user.

Successful exploitation of the vulnerability results in arbitrary code execution on the vulnerable system.

Note: this vulnerability was being actively exploited.

External links:

https://technet.microsoft.com/en-us/library/security/968272.aspx
https://technet.microsoft.com/en-us/library/security/ms09-009.aspx
https://www.symantec.com/security_response/writeup.jsp?docid=2009-022310-4202-99
https://www.secureworks.com/blog/research-20953
https://www.us-cert.gov/ncas/alerts/TA09-104A
http://blog.trendmicro.co.jp/archives/2596
https://www.publicsafety.gc.ca/cnt/rsrcs/cybr-ctr/2009/av09-018-eng.aspx
https://downloads.avaya.com/css/P8/documents/100063922
https://www.paulstechtalk.com/2009/04/microsoft-released-april-patch-list-for-patch-tuesday/

About zero-day vulnerabilities

Zero-day vulnerability is an undisclosed vulnerability in software that hackers can exploit to compromise computer programs, gain unauthorized access to sensitive data, penetrate networks, etc. We consider vulnerability a zero-day when there is no solution provided from software vendor and the vulnerability is being actively exploited by malicious actors.

Zero-day candidate is a potential zero-day vulnerability in software which might have been used in targeted attacks, however there is no evidence to support this suggestion.