CVE-2017-18049 in SilverStripe
Summary
by MITRE
In the CSV export feature of SilverStripe before 3.5.6, 3.6.x before 3.6.3, and 4.x before 4.0.1, it's possible for the output to contain macros and scripts, which may be executed if imported without sanitization into common software (including Microsoft Excel). For example, the CSV data may contain untrusted user input from the "First Name" field of a user's /myprofile page.
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Analysis
by VulDB Data Team • 12/29/2019
The vulnerability identified as CVE-2017-18049 represents a critical security flaw in the SilverStripe content management system's CSV export functionality across multiple versions. This issue stems from inadequate input sanitization within the export mechanism, creating a vector for malicious code injection that can lead to remote code execution when imported into spreadsheet applications. The vulnerability specifically affects SilverStripe versions prior to 3.5.6, 3.6.3, and 4.0.1, making it a widespread concern for organizations using these older versions of the platform. The flaw is particularly dangerous because it leverages the inherent trust users place in spreadsheet applications, where CSV files are often automatically executed when opened, creating a perfect storm for exploitation.
The technical root cause of this vulnerability lies in the improper handling of user input during CSV generation processes. When users submit data through forms such as the "First Name" field on profile pages, the system fails to adequately sanitize or escape special characters that could be interpreted as spreadsheet macros or executable commands. This weakness directly maps to CWE-15 (External Control of System or Configuration Setting) and CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component) within the Common Weakness Enumeration framework. The vulnerability allows attackers to inject malicious payloads such as Excel formulas beginning with equals signs, VBA macros, or other script-like constructs that execute automatically when the CSV file is opened in applications like Microsoft Excel. The attack surface is broadened by the fact that these applications automatically interpret certain CSV content as executable code without proper validation.
The operational impact of this vulnerability extends far beyond simple data corruption or unauthorized access. Organizations using affected SilverStripe versions face significant risks including potential data breaches, system compromise, and unauthorized code execution on end-user machines. When malicious actors exploit this vulnerability, they can inject malware, steal sensitive information, or establish persistent access to compromised systems through the spreadsheet application's automatic execution features. The vulnerability also creates indirect risks for organizations that may unknowingly distribute infected CSV files to employees, potentially leading to widespread compromise across an enterprise network. This type of vulnerability is particularly concerning in the context of the MITRE ATT&CK framework, specifically mapping to techniques involving execution through macro and script injection, where adversaries leverage trusted applications to bypass traditional security controls.
Mitigation strategies for CVE-2017-18049 require immediate attention through version upgrades to patched SilverStripe releases, as well as implementing additional defensive measures. Organizations should prioritize upgrading to SilverStripe 3.5.6, 3.6.3, or 4.0.1, depending on their current version, to receive the core security fixes. Beyond version control, administrators should implement comprehensive input validation and sanitization policies for all user-submitted data, particularly in fields that may be exported to CSV format. The implementation of proper escaping mechanisms for special characters, including equals signs, at symbols, and other potentially dangerous CSV delimiters, becomes essential. Network-level protections such as email filtering and file type restrictions can provide additional defense in depth, while user education regarding the dangers of opening untrusted CSV files in spreadsheet applications remains critical. Regular security audits of export functionalities and input handling mechanisms should be conducted to identify similar vulnerabilities, with automated testing tools integrated into development workflows to prevent such issues from recurring in future releases.