CVE-2017-8102 in Serendipity
Summary
by MITRE
Stored XSS in Serendipity v2.1-rc1 allows an attacker to steal an admin's cookie and other information by composing a new entry as an editor user. This is related to lack of the serendipity_event_xsstrust plugin and a set_config error in that plugin.
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Analysis
by VulDB Data Team • 12/02/2022
The vulnerability CVE-2017-8102 represents a critical stored cross-site scripting flaw in Serendipity v2.1-rc1 that enables attackers to execute malicious scripts in the context of administrative sessions. This weakness arises from insufficient input validation and output sanitization mechanisms within the content management system's entry creation functionality. The vulnerability specifically affects scenarios where editor users compose new entries, creating a persistent attack vector that can compromise administrative privileges and access sensitive information.
The technical root cause stems from the absence of proper security controls within the serendipity_event_xsstrust plugin, which is responsible for managing cross-site scripting protections. Additionally, a configuration error within this same plugin exacerbates the vulnerability by failing to properly validate or sanitize user input before storing it in the database. This dual failure creates a condition where malicious payloads can be stored in the system's content management database and subsequently executed whenever administrative users view the affected entries. The flaw aligns with CWE-79 which categorizes cross-site scripting vulnerabilities as weaknesses in input validation and output encoding.
The operational impact of this vulnerability is severe as it allows attackers to steal administrative cookies and session tokens, effectively granting them full control over the affected Serendipity installation. Once an attacker successfully injects malicious scripts into stored content, they can execute arbitrary code in the browser of any administrator who views the compromised entries. This enables session hijacking, privilege escalation, and potential lateral movement within the compromised environment. The vulnerability also falls under ATT&CK technique T1566 which describes social engineering attacks that can lead to credential theft and unauthorized access.
Mitigation strategies should focus on immediate plugin updates and configuration corrections to ensure proper input validation and output sanitization. Organizations must implement comprehensive content security policies that enforce strict validation of all user-generated content before storage. The recommended approach includes upgrading to patched versions of Serendipity, implementing proper input sanitization routines, and configuring the xsstrust plugin with appropriate security parameters. Additionally, network monitoring should be enhanced to detect suspicious script injection patterns, while regular security audits should verify that all plugins maintain proper security configurations to prevent similar vulnerabilities from emerging in the future.