CVE-2018-9107 in AcyMailing Extension
Summary
by MITRE
CSV Injection (aka Excel Macro Injection or Formula Injection) exists in the export feature in the Acyba AcyMailing extension before 5.9.6 for Joomla! via a value that is mishandled in a CSV export.
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Analysis
by VulDB Data Team • 05/31/2025
The vulnerability CVE-2018-9107 represents a critical csv injection flaw within the Acyba AcyMailing extension for Joomla! systems, specifically affecting versions prior to 5.9.6. This vulnerability falls under the category of formula injection attacks where malicious input can be executed when csv files are opened in spreadsheet applications like Microsoft Excel or LibreOffice Calc. The issue stems from improper sanitization of user-supplied data during the csv export functionality, allowing attackers to craft malicious payloads that execute arbitrary code when the exported file is opened in a spreadsheet application. The vulnerability is particularly dangerous because it leverages the inherent behavior of spreadsheet applications that automatically interpret certain characters as formula commands, making it a prime target for social engineering attacks where users are tricked into opening malicious csv files.
The technical exploitation of this vulnerability occurs when the Acyba AcyMailing extension processes user input for csv export operations without adequate validation or sanitization. When a malicious payload begins with specific characters such as equals signs, plus signs, or minus signs followed by formula commands, spreadsheet applications automatically interpret these as executable formulas rather than plain text. This behavior creates a dangerous attack surface where an attacker can inject malicious formulas that execute when the csv file is opened, potentially leading to remote code execution, data theft, or system compromise. The vulnerability is classified as a CWE-1236 weakness in the context of formula injection, specifically targeting the improper handling of user input in export functionality. According to ATT&CK framework, this represents a technique categorized under T1059.005 - Command and Scripting Interpreter: Visual Basic, as the injection targets spreadsheet applications that interpret formulas as executable commands.
The operational impact of CVE-2018-9107 extends beyond simple data corruption or display issues, as it can enable full system compromise when exploited successfully. Attackers can leverage this vulnerability to execute arbitrary code on victim systems with the privileges of the spreadsheet application user, potentially leading to complete system takeover. The vulnerability affects Joomla! websites using the Acyba AcyMailing extension, making it particularly concerning for organizations that rely on email marketing automation tools. The attack vector typically involves social engineering where users are诱导ed to download and open malicious csv files, often disguised as legitimate export data. Organizations with multiple users who frequently handle email marketing data are at heightened risk, as the vulnerability can be exploited through simple user interaction without requiring advanced technical skills from the attacker. The vulnerability's impact is further amplified in enterprise environments where email marketing systems may contain sensitive user data, campaign information, or business-critical data that could be accessed or modified by unauthorized parties.
Mitigation strategies for CVE-2018-9107 primarily focus on immediate patching and implementation of defensive measures. The most effective solution is upgrading the Acyba AcyMailing extension to version 5.9.6 or later, which includes proper input sanitization and validation for csv export functionality. Organizations should also implement input validation at multiple layers, ensuring that user-supplied data is properly escaped or sanitized before being included in csv export files. Network administrators should consider implementing content filtering solutions that can detect and block potentially malicious csv files, particularly those containing formula injection patterns. Additionally, user education and awareness programs should emphasize the dangers of opening csv files from untrusted sources, as the vulnerability relies heavily on social engineering tactics. Security teams should monitor for suspicious csv file downloads and implement strict access controls for email marketing systems, limiting the attack surface where this vulnerability could be exploited. The implementation of web application firewalls and security monitoring solutions can help detect and prevent exploitation attempts, while regular security audits should verify that all email marketing and export functionalities properly sanitize user input to prevent similar vulnerabilities from emerging in the future.