CVE-2021-42112 in LimeSurvey
Summary
by MITRE • 10/09/2021
The "File upload question" functionality in LimeSurvey 3.x-LTS through 3.27.18 allows XSS in assets/scripts/modaldialog.js and assets/scripts/uploader.js.
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Analysis
by VulDB Data Team • 10/14/2021
The vulnerability CVE-2021-42112 represents a cross-site scripting vulnerability within LimeSurvey's file upload question functionality affecting versions 3.x-LTS through 3.27.18. This issue specifically impacts the javascript files modaldialog.js and uploader.js located in the assets/scripts directory of the application. The flaw arises from insufficient input validation and output encoding when processing file upload responses, creating an avenue for malicious actors to inject malicious javascript code into the application's response stream.
The technical implementation of this vulnerability stems from improper sanitization of user-supplied data within the file upload handling process. When users upload files through the question functionality, the application processes these uploads and generates javascript responses that are subsequently executed in the browser context. The modaldialog.js and uploader.js files fail to properly encode or escape special characters in the file names or metadata, allowing attackers to inject malicious javascript payloads that execute in the context of other users' browsers. This type of vulnerability falls under CWE-79 which specifically addresses cross-site scripting flaws due to insufficient input validation and output encoding.
The operational impact of this vulnerability extends beyond simple script execution as it enables attackers to perform a range of malicious activities including session hijacking, data exfiltration, and privilege escalation. An attacker could craft malicious file names containing javascript code that would execute when other users view the upload results or interact with the file management interface. This creates a persistent threat vector where the malicious code executes automatically whenever affected users access the vulnerable functionality. The attack surface is particularly concerning given that LimeSurvey is commonly used for sensitive data collection and survey administration, making the potential for data compromise significant.
Security professionals should consider this vulnerability in relation to the ATT&CK framework's T1566 technique for Initial Access through spearphishing attachments, as attackers could leverage this vulnerability to deliver malicious payloads through file uploads. Additionally, the vulnerability aligns with T1071.004 for application layer protocol usage and T1505.003 for additional software or hardware components, as it affects the javascript execution environment and file handling components of the application. Organizations should prioritize immediate patching of affected LimeSurvey installations to address this vulnerability and implement proper input validation and output encoding measures throughout their application codebase. The remediation process should include comprehensive code review of all javascript files handling user input and implementation of strict sanitization protocols to prevent similar issues in future development cycles.