CVE-2021-24384 in JoomSport Plugin
Summary
by MITRE • 07/06/2021
The joomsport_md_load AJAX action of the JoomSport WordPress plugin before 5.1.8, registered for both unauthenticated and unauthenticated users, unserialised user input from the shattr POST parameter, leading to a PHP Object Injection issue. Even though the plugin does not have a suitable gadget chain to exploit this, other installed plugins could, which might lead to more severe issues such as RCE
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Analysis
by VulDB Data Team • 07/09/2021
The vulnerability CVE-2021-24384 resides within the JoomSport WordPress plugin ecosystem, specifically targeting versions prior to 5.1.8 where the joomsport_md_load AJAX action presents a critical security flaw. This issue manifests through improper input validation and sanitization mechanisms that allow malicious actors to inject serialized PHP objects via the shattr POST parameter. The vulnerability operates at the intersection of insecure deserialization practices and the broader WordPress plugin architecture, creating a potential attack vector that extends beyond the immediate plugin scope.
The technical flaw represents a classic PHP Object Injection vulnerability, categorized under CWE-502, where user-controllable data is passed directly to unserialize() functions without adequate validation. The vulnerability is particularly concerning because the AJAX endpoint is registered for both authenticated and unauthenticated users, expanding the attack surface significantly. When the plugin processes the shattr parameter through the joomsport_md_load action, it fails to properly sanitize the input before attempting to deserialize it, creating an opportunity for attackers to craft malicious serialized objects that could execute arbitrary code when processed.
The operational impact of this vulnerability extends well beyond the immediate plugin scope due to the interconnected nature of WordPress environments. While the JoomSport plugin itself may not contain suitable gadget chains for exploitation, the presence of malicious serialized objects opens the door for exploitation through other installed plugins that might have vulnerable deserialization gadgets. This creates a cascading effect where a single vulnerability in one plugin can potentially lead to full system compromise through the exploitation of gadget chains present in other installed plugins, making this a particularly dangerous vulnerability in typical WordPress installations where multiple plugins are commonly deployed.
Security practitioners should recognize this vulnerability through the ATT&CK framework's T1203 (Exploitation for Client Execution) and T1059 (Command and Scripting Interpreter) techniques, as it enables attackers to potentially execute arbitrary code through object injection. The remediation strategy must focus on immediate patching to version 5.1.8 or later, which addresses the improper input handling in the AJAX endpoint. Additionally, implementing input validation and sanitization measures, including the use of allowlists for accepted parameters, can provide defense-in-depth protection. Organizations should also conduct comprehensive audits of all installed plugins to identify potential gadget chains that could be exploited in conjunction with this vulnerability, as the presence of other vulnerable plugins in the environment significantly increases the risk profile of the system.