CVE-2016-4874 in Cybozu Office
Summary
by MITRE
Cybozu Office 9.0.0 through 10.4.0 allows remote attackers to conduct a "reflected file download" attack.
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Analysis
by VulDB Data Team • 08/31/2020
The vulnerability identified as CVE-2016-4874 affects Cybozu Office versions 9.0.0 through 10.4.0 and represents a critical security flaw that enables remote attackers to execute reflected file download attacks. This type of vulnerability falls under the category of web application security weaknesses where malicious actors can manipulate application behavior to trick users into downloading and executing arbitrary files from remote servers. The flaw specifically exploits how the application handles user input in URLs, creating a pathway for attackers to inject malicious file names that get reflected back to the victim's browser.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization within the Cybozu Office application's web interface. When users navigate to specific URLs containing crafted parameters, the application fails to properly sanitize these inputs before incorporating them into file download operations. This creates an environment where attackers can inject malicious file names or paths that appear legitimate to the user's browser, causing the system to initiate downloads of files from attacker-controlled servers. The reflected nature of this attack means that the malicious payload is embedded within the HTTP response itself, making it particularly difficult to detect and prevent through traditional network monitoring approaches.
From an operational impact perspective, this vulnerability presents a severe risk to organizations using affected Cybozu Office versions as it allows attackers to bypass standard security controls and directly compromise end-user systems. Successful exploitation could result in the automatic download and execution of malware, including trojans, ransomware, or other malicious payloads that could lead to complete system compromise, data exfiltration, or further network infiltration. The attack vector typically involves sending phishing emails or compromising legitimate websites that redirect users to malicious URLs, making it particularly dangerous in enterprise environments where users may trust familiar applications and interfaces. This vulnerability directly aligns with CWE-434 which categorizes insecure file upload and download practices, and represents a clear violation of secure coding principles for input validation.
Organizations should immediately implement comprehensive mitigation strategies to address this vulnerability, beginning with urgent patch deployment to upgrade to versions of Cybozu Office that have resolved this issue. Network administrators should also consider implementing web application firewalls and content filtering solutions that can detect and block malicious URL patterns associated with reflected file download attacks. Additionally, user education and awareness programs should emphasize the importance of verifying download sources and avoiding suspicious links, particularly when navigating to applications that may be vulnerable to such attacks. The remediation process should include thorough security testing to ensure that no other similar vulnerabilities exist within the application's codebase, and organizations should conduct regular vulnerability assessments to identify and address potential security gaps. This vulnerability demonstrates the critical importance of maintaining up-to-date software versions and implementing layered security controls to protect against sophisticated attack vectors that exploit application-level weaknesses. The attack pattern associated with this vulnerability is consistent with techniques described in the MITRE ATT&CK framework under the T1193 category for Spearphishing Attachments, highlighting the need for comprehensive email security and endpoint protection measures to prevent successful exploitation.