Perl Spreadsheet::ParseExcel Arbitrary Code Execution Vulnerability Advisory (CVE-2023-7101)
Executive & SecOps Summary
SECOPS ASSESSMENTAll applications utilizing Spreadsheet::ParseExcel library version 0.65 and prior
Remote attackers can execute arbitrary Perl code and gain full system privileges by tricking the application into parsing a specially crafted Excel file
Immediately upgrade the Spreadsheet::ParseExcel module to the patched version (0.66 or later)
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Update the Spreadsheet::ParseExcel module to the latest secure version (0.66 or higher) using the CPAN package manager.
# Upgrade the module via CPAN
perl -MCPAN -e 'install Spreadsheet::ParseExcel'
# Alternatively, using cpanm (CPAN minus)
cpanm --force Spreadsheet::ParseExcel2. Temporary Workaround & Hardening Configuration
If patching cannot be applied immediately, restrict or disable Excel file uploads from untrusted sources. Implement strict egress filtering on the servers running the Perl parser to prevent reverse shell connections in case of exploitation.
# Restrict outbound connections for the web server user (e.g., 'www-data')
iptables -A OUTPUT -m owner --uid-owner www-data -p tcp --dport 80 -j ACCEPT
iptables -A OUTPUT -m owner --uid-owner www-data -p tcp --dport 443 -j ACCEPT
iptables -A OUTPUT -m owner --uid-owner www-data -j DROP3. Log Audit & IoC Verification Commands
Run the following commands to check the installed version of the module and inspect the codebase for the vulnerable pattern.
# Check the installed version of Spreadsheet::ParseExcel
perl -MSpreadsheet::ParseExcel -e 'print $Spreadsheet::ParseExcel::VERSION . "\
"'
# Search for the vulnerable eval pattern in Utility.pm
find / -name "Utility.pm" 2>/dev/null | xargs grep -n "eval.*format"Scan Your Repositories for Transitive Vulnerable Dependencies in 30 Seconds
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Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2023-7101) is an arbitrary code execution (ACE) vulnerability in Spreadsheet::ParseExcel, a widely used Perl module for parsing Excel files. The root cause lies in the evaluation of Number format strings within the Excel parsing logic. Specifically, the module passes unvalidated input from a file into a string-type eval statement within the Utility.pm component, leading to code injection.
2. Exploitation Mechanics & Attack Scenario
An attacker crafts a malicious Excel file (.xls) containing a specially designed Number format string. When the target application parses this file using Spreadsheet::ParseExcel, the parsing engine processes the format string. Due to the lack of input validation, the malicious payload is directly evaluated by Perl's eval function. This bypasses application controls, allowing the attacker to execute arbitrary system commands under the security context of the running Perl process (CWE-94 / CWE-95).
3. Infrastructure & Business Impact
As this vulnerability is listed in the CISA KEV catalog, it has been actively exploited in the wild. Since Spreadsheet::ParseExcel is commonly integrated into email gateways, file upload portals, and automated financial processing pipelines, successful exploitation can grant attackers initial access to internal networks. This can lead to severe consequences, including lateral movement, data exfiltration, and ransomware deployment.
Official Vendor Advisories & References
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.
Frequently Asked SecOps Questions (CVE-2023-7101)
FAQQ1. How critical is CVE-2023-7101 and is it actively exploited in the wild?
CVE-2023-7101 is rated CVSS 7.8 (HIGH) with a 30-day EPSS exploitation probability of 19.0%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2023-7101?
Primary impacted vendors include perl across spreadsheet-parseexcel. Scope summary: Spreadsheet::ParseExcel version 0.65 and prior (Perl CPAN module)
Q3. What temporary mitigations or workarounds exist for CVE-2023-7101 before patching?
[Mitigation] Immediately upgrade the Spreadsheet::ParseExcel module to the patched version (0.66 or later) Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
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