CVE-2023-7101 is an arbitrary code execution vulnerability identified in version 0.65 of the Perl module Spreadsheet::ParseExcel, authored by Douglas Wilson. The module is designed to parse Microsoft Excel files, specifically extracting data from spreadsheets. The vulnerability stems from improper neutralization of directives in dynamically evaluated code (CWE-95), where Number format strings embedded in Excel files are passed without validation into a string-type eval function. This unsafe eval usage allows an attacker to craft malicious Excel files containing specially formatted Number strings that, when parsed, execute arbitrary Perl code on the host system. The vulnerability requires user interaction, as the victim must open or process the malicious Excel file using the vulnerable module. The CVSS v3.1 score is 7.8 (high), reflecting local attack vector (AV:L), low attack complexity (AC:L), no privileges required (PR:N), but requiring user interaction (UI:R). The impact affects confidentiality, integrity, and availability (all high). No patches or fixes are currently linked, and no known exploits have been reported in the wild. This vulnerability is particularly dangerous in environments where untrusted Excel files are processed automatically or manually using this Perl module, potentially leading to full system compromise.

For European organizations, the impact of CVE-2023-7101 can be significant, especially in sectors relying on Perl-based data processing pipelines involving Excel files, such as finance, government, healthcare, and research institutions. Successful exploitation can lead to arbitrary code execution, allowing attackers to steal sensitive data, alter or destroy information, or disrupt services. Since the vulnerability requires user interaction, phishing or social engineering campaigns delivering malicious Excel files could be effective attack vectors. The compromise could extend to lateral movement within networks, data exfiltration, or deployment of ransomware. Organizations automating Excel file ingestion without strict validation are particularly vulnerable. The confidentiality of personal data protected under GDPR could be jeopardized, leading to regulatory and reputational consequences. The lack of known exploits in the wild reduces immediate risk but does not eliminate the threat, as attackers may develop exploits rapidly once the vulnerability is public.

1. Immediately audit all systems and applications using Spreadsheet::ParseExcel version 0.65 to identify exposure. 2. If possible, upgrade to a patched or newer version of the module that removes unsafe eval usage; if no patch exists, consider applying custom patches to sanitize Number format strings before evaluation. 3. Implement strict input validation and sanitization on all Excel files before processing, especially focusing on Number format strings. 4. Restrict the processing of Excel files from untrusted or external sources and employ sandboxing or isolated environments for parsing. 5. Educate users about the risks of opening Excel files from unknown or suspicious origins to reduce the likelihood of social engineering exploitation. 6. Monitor logs and system behavior for unusual activity indicative of code execution or compromise related to Excel file processing. 7. Employ application whitelisting and endpoint detection and response (EDR) tools to detect and block unauthorized code execution. 8. Consider alternative libraries or tools for Excel parsing that do not rely on unsafe eval constructs. 9. Coordinate with internal security teams to update incident response plans to include this threat vector.