CVE-2023-7101 in Spreadsheet::ParseExcel
Summary
by MITRE • 12/25/2023
Spreadsheet::ParseExcel version 0.65 is a Perl module used for parsing Excel files. Spreadsheet::ParseExcel is vulnerable to an arbitrary code execution (ACE) vulnerability due to passing unvalidated input from a file into a string-type “eval”. Specifically, the issue stems from the evaluation of Number format strings (not to be confused with printf-style format strings) within the Excel parsing logic.
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Analysis
by VulDB Data Team • 04/20/2025
The Spreadsheet::ParseExcel Perl module version 0.65 contains a critical arbitrary code execution vulnerability that poses significant security risks to systems processing Excel files. This vulnerability arises from the module's handling of number format strings during Excel file parsing operations, creating a pathway for malicious code injection. The flaw specifically occurs when the module processes unvalidated input from Excel files and passes it directly into a string-type eval function, which executes the malformed code within the context of the running Perl process.
This vulnerability operates at the intersection of several security concerns including code injection and privilege escalation. The attack vector involves crafting a malicious Excel file with specially formatted number formats that contain executable Perl code. When the vulnerable module processes such a file, the format string evaluation triggers the execution of the embedded malicious code, potentially allowing attackers to perform arbitrary operations on the affected system. The vulnerability is particularly dangerous because it can be exploited through routine file processing operations without requiring any special privileges or user interaction beyond opening the file.
The technical implementation of this vulnerability aligns with CWE-94, which describes the weakness of allowing code to be executed as a result of untrusted input being passed to an eval() function. The module's parsing logic does not adequately validate or sanitize the number format strings extracted from Excel files, creating a direct path for code injection attacks. This flaw represents a classic example of insecure deserialization where structured data from external sources is directly interpreted without proper validation. The operational impact extends beyond simple code execution to potentially allow full system compromise, data exfiltration, or lateral movement within network environments where the vulnerable module is deployed.
Organizations using Spreadsheet::ParseExcel version 0.65 are at risk of sophisticated attacks that can leverage this vulnerability for persistent access and data theft. The vulnerability affects systems that process Excel files from untrusted sources, including automated data processing pipelines, web applications accepting file uploads, and any application that relies on the module for Excel file parsing. Security practitioners should consider this vulnerability in their threat modeling and incident response planning, as it can be exploited through various attack vectors including email attachments, file upload portals, and automated data import processes. The risk assessment should include evaluation of systems where the module is used in web applications, file processing services, and any environment where Excel files from external sources are automatically parsed and processed.
Mitigation strategies should focus on immediate remediation through module version updates to address the vulnerability, while also implementing additional security controls such as input validation, file type restrictions, and sandboxed processing environments. Organizations should conduct comprehensive vulnerability assessments to identify all systems using the affected module and implement network segmentation to limit potential lateral movement if exploitation occurs. The ATT&CK framework categorizes this vulnerability under T1059.007 for command and scripting interpreter, highlighting the need for process monitoring and behavioral analysis to detect suspicious code execution patterns. Regular security updates and patch management procedures should be enforced to prevent similar vulnerabilities in other Perl modules and applications that may be susceptible to similar code injection flaws.