CVE-2008-3471: Microsoft Excel BIFF file parsing stack buffer overflow

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 20 September 2026. Confidence: high.

high priorityRemote code execution with complete impact and a very high EPSS score, tempered by the requirement that a user open a crafted file and by the age of the affected products.

What it is

Microsoft Excel and related Excel viewers and converters contain a stack-based buffer overflow when parsing a BIFF file with a malformed record that triggers a user-influenced size calculation. Opening a crafted spreadsheet can corrupt the stack and allow arbitrary code execution in the context of the user. The flaw affects Excel 2000 through 2007, Excel Viewer 2003, the Office Compatibility Pack, Office for Mac 2004/2008, and the Open XML File Format Converter for Mac.

Impact

An attacker who gets a victim to open a malicious BIFF file can execute arbitrary code with the privileges of the logged-on user, giving full control of confidentiality, integrity and availability on that host.

Attack surface

Reached remotely by delivering a crafted BIFF spreadsheet file, typically via email attachment or a hosted download; no authentication is required, but the victim must open the file, which is why the CVSS vector is AV:N/AC:M/Au:N.

Exploitation

Not listed in CISA KEV and no ransomware associations are documented, but EPSS is high at roughly 0.52 (99th percentile), and references include a Zero Day Initiative advisory, indicating public technical detail exists.

What to do

• Apply Microsoft security bulletin MS08-057 for all affected Excel, Excel Viewer, Compatibility Pack, Office for Mac and Open XML File Format Converter installations
• Upgrade off end-of-life Excel 2000/2002/2003 and Office 2004 for Mac to a supported release
• Block or strip untrusted spreadsheet attachments at the mail and web gateway, and enforce Mark-of-the-Web/Protected View so files open in a restricted mode
• Disable or restrict Excel Viewer and the Open XML File Format Converter where they are not operationally required
• Run users with least privilege so code execution does not inherit administrative rights

Detection

• Hunt for Excel, Excel Viewer or Open XML File Format Converter processes spawning child processes such as cmd.exe, powershell.exe or wscript.exe
• Monitor for spreadsheet files written to temp or startup locations shortly after an Office application opens an email or download
• Alert on Office application crashes or stack-corruption events correlated with recently opened BIFF/XLS files
• Review proxy and mail logs for inbound spreadsheet attachments from untrusted senders or newly registered domains

This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.