CVE-2016-6848 in OX AppSuite
Summary
by MITRE
An issue was discovered in Open-Xchange OX App Suite before 7.8.2-rev8. API requests can be used to inject, generate and download executable files to the client ("Reflected File Download"). Malicious platform specific (e.g. Microsoft Windows) batch file can be created via a trusted domain without authentication that, if executed by the user, may lead to local code execution.
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Analysis
by VulDB Data Team • 07/08/2019
The vulnerability identified as CVE-2016-6848 represents a critical security flaw in Open-Xchange OX App Suite versions prior to 7.8.2-rev8, specifically addressing a reflected file download vulnerability that enables attackers to execute arbitrary code on targeted systems. This issue stems from the application's improper handling of API requests that allow for file generation and download operations, creating an avenue for malicious actors to inject executable content directly into client environments. The vulnerability operates by leveraging the application's trusted domain mechanisms to craft malicious batch files that can be downloaded and executed without requiring user authentication, fundamentally undermining the security model of the platform.
The technical exploitation of this vulnerability occurs through API request manipulation that enables the generation of executable files on the client side, specifically targeting Microsoft Windows environments through batch file creation. Attackers can craft malicious requests that result in the creation of .bat files or similar platform-specific executables which are then downloaded to the victim's system. The flaw exists in the application's input validation and output encoding mechanisms, where API responses containing user-supplied data are not properly sanitized before being used in file generation contexts. This creates a reflected file download scenario where the malicious payload is reflected back to the user in a manner that appears legitimate due to the trusted domain origin, making it more likely for users to execute the downloaded files without suspicion.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass full system compromise through local code execution. When victims execute the downloaded batch files, attackers can gain complete control over the compromised systems, potentially leading to data exfiltration, persistent access, or further lateral movement within network environments. The vulnerability's severity is amplified by its ability to operate without authentication requirements, meaning that any user interacting with the application could become a victim. This makes the attack surface particularly broad and difficult to defend against, as it requires no special credentials or complex attack vectors to exploit.
Security practitioners should implement multiple layers of defense to mitigate this vulnerability, beginning with immediate patching to version 7.8.2-rev8 or later, which contains the necessary fixes for the reflected file download issue. Network segmentation and access controls should be strengthened to limit exposure of the vulnerable application to untrusted networks, while web application firewalls can be configured to detect and block suspicious API request patterns that might indicate exploitation attempts. Input validation should be enhanced to ensure all user-supplied data is properly sanitized before being used in file generation contexts, and output encoding should be implemented to prevent malicious content from being reflected back to clients in executable formats. This vulnerability aligns with CWE-434, which specifically addresses the improper restriction of file downloads, and maps to ATT&CK technique T1195.001 for the use of reflected file download attacks. Organizations should also conduct thorough security assessments of their web applications to identify similar vulnerabilities in other systems that might be susceptible to the same class of reflected file download attacks, as the underlying architectural flaws that enable this vulnerability often exist in other applications as well.