CVE-2019-9874 in Sitecore
Summary
by MITRE
Deserialization of Untrusted Data in the Sitecore.Security.AntiCSRF (aka anti CSRF) module in Sitecore CMS 7.0 to 7.2 and Sitecore XP 7.5 to 8.2 allows an unauthenticated attacker to execute arbitrary code by sending a serialized .NET object in the HTTP POST parameter __CSRFTOKEN.
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Analysis
by VulDB Data Team • 03/27/2025
The vulnerability CVE-2019-9874 represents a critical deserialization flaw within Sitecore CMS security components that affects versions ranging from 7.0 through 8.2. This issue resides in the Sitecore.Security.AntiCSRF module, commonly referred to as the anti CSRF module, which is designed to protect web applications against cross-site request forgery attacks. The flaw manifests when the application processes untrusted data through the deserialization mechanism, creating a dangerous attack surface that can be exploited by malicious actors without requiring authentication credentials. The vulnerability specifically targets the __CSRFTOKEN HTTP POST parameter, which is typically used for CSRF protection but becomes a vector for remote code execution when improperly handled.
The technical exploitation of this vulnerability stems from the improper handling of serialized .NET objects within the anti CSRF module's processing pipeline. When an attacker sends a maliciously crafted serialized object through the __CSRFTOKEN parameter, the Sitecore application deserializes this data without adequate validation or sanitization. This deserialization process occurs in a context where the application has sufficient privileges to execute arbitrary code, allowing the attacker to leverage the deserialization vulnerability to achieve remote code execution on the target system. The flaw aligns with CWE-502 which specifically addresses deserialization of untrusted data as a security weakness that can lead to arbitrary code execution. The vulnerability demonstrates a classic insecure deserialization pattern where the application trust the source of serialized data without proper validation.
The operational impact of CVE-2019-9874 is severe and encompasses complete system compromise for affected Sitecore installations. An unauthenticated attacker can execute arbitrary commands on the target server with the privileges of the web application, potentially leading to data exfiltration, system enumeration, and further lateral movement within the network. The vulnerability's exploitation does not require authentication, making it particularly dangerous as it can be leveraged by anyone who can access the target Sitecore application. This flaw essentially provides a backdoor into the system that bypasses traditional authentication mechanisms, allowing attackers to establish persistent access and potentially escalate privileges. The attack surface is broad as any Sitecore installation running the vulnerable versions is at risk, and the exploitation can occur through standard web traffic without requiring specialized tools or conditions.
Mitigation strategies for CVE-2019-9874 should focus on immediate patching of affected Sitecore installations to the latest available versions that contain the necessary security fixes. Organizations should also implement network-level controls such as firewall rules that restrict access to the affected endpoints and monitor for suspicious deserialization patterns in web application logs. The implementation of input validation and sanitization measures can help reduce the attack surface by ensuring that only properly formatted data is processed through the deserialization pipeline. Security teams should also consider implementing runtime application self-protection mechanisms and application firewalls that can detect and block malicious deserialization attempts. According to ATT&CK framework, this vulnerability maps to T1059.001 for command and script interpreter and T1106 for execution of files, representing the execution of malicious code through deserialization attacks. Organizations should also conduct thorough security assessments of their Sitecore installations to identify any additional vulnerabilities in the security module and ensure proper configuration of security controls to prevent exploitation of similar weaknesses in the broader application architecture.