CVE Alert: CVE-2007-0671 – n/a – n/a

Risk verdict

Very high risk: this vulnerability is in the CISA KEV and exploitation is active; treat as priority 1.

Why this matters

Exploitation enables remote code execution on end-user workstations via a crafted Excel file, with no privileges required but user interaction needed. In organisations relying on legacy Office deployments, this can lead to complete endpoint compromise, data exfiltration, or lateral movement, especially where sensitive spreadsheets are routinely shared.

Most likely attack path

An attacker delivers a malicious Excel document (e.g., via email or network share). A user opens it, triggering arbitrary code execution with the attacker’s payload, potentially compromising the host without prior access credentials. Lateral movement would depend on existing trust and network permissions after initial compromise.

Who is most exposed

Businesses with older Excel/Office installations (Windows and Mac) and environments where Office documents are frequently exchanged externally or via email are most at risk, particularly where patching of legacy versions lags behind.

Detection ideas

• Unusual or failed attempts to run Excel processes coupled with anomalous child processes (e.g., launches of shell or scripting runtimes).
• Detection of unusually crafted or macro-enabled workbooks, especially trailing payload indicators in documents.
• Spike in Excel-related network activity or unexpected outbound connections following document open events.
• Event logs showing rapid, abnormal memory/handle usage after opening Excel files.

Mitigation and prioritisation

• Apply MS07-015 or equivalent security updates immediately; confirm patch across Windows and Mac Office installations.
• Implement macro/script controls: disable automatic macros, enable Protected View, and enforce strict attachment scanning.
• Deploy network-level protections: robust email/file gateway filtering for malicious Excel payloads; disable insecure Office features where feasible.
• Enforce least-privilege and segment critical assets to limit post-exploitation movement.
• Change-management: document patch status and verify remediation; treat as priority 1 due to KEV presence and active exploitation. If patching cannot be completed promptly, implement compensating controls and rapid user-awareness messaging.