CVE-2016-4552 in RoundCube
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in Roundcube Webmail before 1.2.0 allows remote attackers to inject arbitrary web script or HTML via the href attribute in an area tag in an e-mail message.
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Analysis
by VulDB Data Team • 10/12/2022
The CVE-2016-4552 vulnerability represents a critical cross-site scripting flaw in Roundcube Webmail versions prior to 1.2.0, specifically targeting the email rendering engine's handling of HTML content. This vulnerability resides in the webmail application's insecure processing of email messages that contain malicious HTML markup, particularly when these messages include area tags with href attributes that can be exploited to execute arbitrary JavaScript code within the context of a user's browser session.
The technical flaw stems from inadequate input sanitization and output encoding mechanisms within Roundcube's email message parser. When the application processes incoming email messages containing HTML content, it fails to properly escape or filter potentially malicious href attributes within area tags, allowing attackers to inject malicious scripts that execute in the victim's browser context. This represents a classic XSS vulnerability categorized under CWE-79, which defines the weakness as the failure to sanitize user-provided data before it is rendered in web applications, creating opportunities for attackers to inject client-side scripts.
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, credential theft, and data exfiltration. An attacker could craft email messages containing malicious href attributes that, when opened by a victim, would execute scripts capable of stealing cookies, redirecting users to phishing sites, or even installing malware on the victim's system. The vulnerability affects any user who opens the malicious email message in the vulnerable Roundcube Webmail interface, making it particularly dangerous in corporate environments where email is a primary communication channel.
The attack vector requires minimal privileges and can be executed through simple email-based social engineering campaigns, making it highly exploitable in real-world scenarios. The vulnerability aligns with ATT&CK technique T1566, which describes the use of spearphishing emails as initial access vectors, and T1059, which covers the execution of malicious code through web-based interfaces. Organizations using vulnerable versions of Roundcube Webmail face significant risk as this flaw can be exploited by attackers without requiring any special privileges or complex attack chains.
Mitigation strategies should include immediate upgrading to Roundcube Webmail version 1.2.0 or later, which contains the necessary patches to address the XSS vulnerability. Additionally, organizations should implement robust email filtering solutions that can detect and quarantine suspicious HTML content, deploy Content Security Policy (CSP) headers to limit script execution, and educate users about the risks of opening untrusted email messages. Security configurations should also include proper input validation and output encoding mechanisms to prevent similar vulnerabilities in other applications within the email ecosystem. The vulnerability demonstrates the critical importance of maintaining up-to-date web applications and implementing defense-in-depth strategies to protect against email-based attacks that can bypass traditional network security controls.