CVE-2016-9752 in Serendipity
Summary
by MITRE
In Serendipity before 2.0.5, an attacker can bypass SSRF protection by using a malformed IP address (e.g., http://127.1) or a 30x (aka Redirection) HTTP status code.
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Analysis
by VulDB Data Team • 10/04/2022
The vulnerability identified as CVE-2016-9752 affects Serendipity CMS versions prior to 2.0.5 and represents a significant server-side request forgery flaw that undermines the application's security controls. This vulnerability allows malicious actors to circumvent intended protection mechanisms designed to prevent unauthorized access to internal network resources. The issue stems from insufficient validation of IP address formats and HTTP redirection handling within the application's request processing logic.
The technical flaw manifests through two primary attack vectors that exploit weaknesses in input validation and response handling. First, attackers can utilize malformed IP address representations such as http://127.1 which, due to improper parsing, may be interpreted as valid internal addresses despite being malformed. This bypasses standard IP address validation checks that would normally reject such inputs. Second, the vulnerability permits exploitation through 30x HTTP status codes, where the application fails to properly validate or reject redirected requests that should be blocked. This dual attack surface demonstrates a fundamental weakness in the application's request filtering mechanisms.
The operational impact of this vulnerability is substantial as it enables attackers to potentially access internal services, databases, or other sensitive resources that should remain isolated from external access. An attacker could leverage this flaw to perform reconnaissance on internal network components, access internal APIs, or even escalate privileges within the application environment. The vulnerability essentially undermines the security boundary that separates external user inputs from internal system resources, creating a potential pathway for lateral movement within compromised networks. This type of vulnerability is particularly dangerous in environments where internal services are not properly isolated or where the application has access to sensitive internal resources.
The vulnerability aligns with CWE-918, which addresses server-side request forgery in web applications, and can be mapped to ATT&CK technique T1071.004 for application layer protocol manipulation. Organizations should implement comprehensive input validation that properly sanitizes IP addresses and rejects malformed representations. Additionally, HTTP redirection handling should be strengthened to ensure that all redirect responses are properly validated and that internal address ranges are strictly enforced. The recommended mitigation involves upgrading to Serendipity 2.0.5 or later versions where the vulnerability has been patched. Security teams should also implement network-level controls and monitoring to detect anomalous request patterns that may indicate exploitation attempts. Proper security configuration of the application's network access controls and regular security assessments are essential to prevent unauthorized access to internal resources through such vulnerabilities.