CVE-2021-23758 in AjaxPro
Summary
by MITRE • 12/03/2021
All versions of package ajaxpro.2 are vulnerable to Deserialization of Untrusted Data due to the possibility of deserialization of arbitrary .NET classes, which can be abused to gain remote code execution.
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Analysis
by VulDB Data Team • 12/09/2021
The vulnerability identified as CVE-2021-23758 affects the ajaxpro.2 package, a popular .NET library used for web application development. This issue represents a critical deserialization flaw that allows attackers to exploit the application's data processing mechanisms. The vulnerability exists in all versions of the package and stems from insufficient validation of serialized data inputs, creating an attack surface where malicious payloads can be executed within the target system's context. This type of vulnerability falls under the category of insecure deserialization, which is classified as CWE-502 in the Common Weakness Enumeration catalog. The attack vector leverages the inherent trust placed in serialized objects, where the application deserializes data without proper sanitization or validation checks.
The technical exploitation of this vulnerability occurs when an attacker can manipulate serialized data sent to the application, particularly through HTTP requests or API endpoints that utilize the ajaxpro.2 library. The deserialization process in .NET applications can be manipulated to instantiate arbitrary .NET classes, potentially leading to remote code execution. Attackers can craft malicious serialized objects that, when processed by the vulnerable application, trigger the execution of arbitrary code on the target server. This exploitation capability aligns with ATT&CK technique T1059.001 for command and scripting interpreter, and T1203 for Exploitation for Client Execution. The vulnerability is particularly dangerous because it can be leveraged without requiring authentication, making it a significant threat to web applications that rely on this library for data processing or communication.
The operational impact of CVE-2021-23758 extends beyond simple remote code execution, as it can lead to complete system compromise and data breaches. Once an attacker gains execution privileges, they can establish persistent access, escalate privileges, and move laterally within the network infrastructure. The vulnerability affects applications that handle serialized data from untrusted sources, particularly web services, APIs, and any components that deserialize user-provided input. Organizations using this library across their web applications face potential exposure to advanced persistent threats, data exfiltration, and service disruption. The vulnerability's severity is compounded by the fact that it affects all versions of the package, meaning that even patched applications may still be vulnerable if they have not properly updated or removed the affected library from their dependencies. This makes the vulnerability particularly challenging to remediate at scale, as it requires comprehensive dependency auditing and patch management processes. The attack surface is broad, encompassing any web application that utilizes the ajaxpro.2 library for data serialization or communication purposes, making it a critical concern for organizations maintaining multiple web applications or services that may unknowingly include this vulnerable component. Mitigation strategies should include immediate removal or replacement of the vulnerable package, implementation of proper input validation, and deployment of web application firewalls to detect and block malicious serialization attempts.
The vulnerability demonstrates the persistent nature of deserialization attacks in modern web applications, where legacy libraries and frameworks continue to pose risks even after their initial release. Organizations must maintain comprehensive inventory management of all dependencies and regularly audit their applications for known vulnerable components. The attack pattern associated with this vulnerability aligns with the broader threat landscape of automated exploitation tools targeting known vulnerabilities in web frameworks and libraries. Security teams should implement continuous monitoring for exploitation attempts and establish incident response procedures specifically addressing deserialization vulnerabilities. The complexity of this issue requires both immediate patching and long-term architectural considerations to prevent similar vulnerabilities from emerging in other parts of the application stack. The remediation process involves not just updating the affected library but also ensuring that all related applications and services are properly scanned for potential compromise and that appropriate security controls are implemented to prevent future occurrences of similar vulnerabilities.