CVE-2021-43673 in dzzoffice
Summary
by MITRE • 12/03/2021
dzzoffice 2.02.1_SC_UTF8 is affected by a Cross Site Scripting (XSS) vulnerability in explorerfile.php. The output of exit function will be print for the user exit(json_encode($return)).
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Analysis
by VulDB Data Team • 12/09/2021
The vulnerability identified as CVE-2021-43673 affects dzzoffice version 2.02.1_SC_UTF8 and represents a cross site scripting vulnerability located within the explorerfile.php component. This issue arises from improper handling of user input data that flows through the system's exit function, where json_encode($return) is executed and subsequently printed to the user interface. The flaw exists in the application's output rendering mechanism, where encoded JSON data containing potentially malicious script content is directly embedded into the web response without adequate sanitization or context-appropriate encoding.
The technical implementation of this vulnerability stems from the application's failure to properly escape or sanitize data before it is rendered in the browser context. When the exit function processes the json_encode($return) output, it does not perform context-aware encoding that would prevent malicious javascript code from executing within the victim's browser session. This represents a classic XSS vulnerability where user-controllable data flows through the application's execution path and ultimately reaches the web client without proper security measures. The vulnerability aligns with CWE-79 which categorizes cross site scripting flaws as weaknesses in input validation and output encoding.
From an operational impact perspective, this vulnerability enables attackers to execute malicious scripts within the context of authenticated user sessions, potentially leading to session hijacking, data exfiltration, or privilege escalation. An attacker could craft malicious input that, when processed by the explorerfile.php component, would inject javascript payloads into the JSON response. These payloads would execute in the browser of any user who views the affected content, creating a persistent threat vector that could compromise multiple users depending on the application's access controls and user base. The vulnerability specifically affects the application's file explorer functionality, making it particularly dangerous for organizations that rely heavily on document management and file sharing capabilities.
Security mitigations for this vulnerability should focus on implementing proper output encoding and input validation mechanisms throughout the application's data flow. The most effective approach involves applying context-appropriate encoding before any user-controllable data is rendered in the browser, specifically implementing JSON encoding for data destined for JSON contexts. Organizations should also implement Content Security Policy headers to limit script execution and employ proper input sanitization techniques that validate and filter all user-supplied data. Additionally, the application should utilize parameterized queries and proper escape sequences to prevent malicious content from being processed through the exit function. This vulnerability demonstrates the importance of following secure coding practices and adhering to ATT&CK framework techniques related to command and control communications and credential access, as the successful exploitation could lead to broader system compromise. The remediation process should include thorough code review of all file handling components and implementation of automated security testing to prevent similar issues from emerging in future releases.