CVE-2020-20136 in Lean
Summary
by MITRE • 12/15/2020
QuantConnect Lean versions from 2.3.0.0 to 2.4.0.1 are affected by an insecure deserialization vulnerability due to insecure configuration of TypeNameHandling property in Json.NET library.
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Analysis
by VulDB Data Team • 12/17/2020
The vulnerability CVE-2020-20136 represents a critical insecure deserialization flaw in QuantConnect Lean platform versions ranging from 2.3.0.0 to 2.4.0.1. This issue stems from improper configuration of the TypeNameHandling property within the Json.NET library, which serves as the primary serialization framework for data exchange within the platform. The affected versions of QuantConnect Lean utilize this library to handle various data structures including algorithm configurations, backtesting parameters, and trading strategies, making the vulnerability particularly dangerous given the platform's widespread use in algorithmic trading and quantitative finance applications.
The technical root cause of this vulnerability lies in the insecure configuration of the TypeNameHandling property set to TypeNameHandling.All or TypeNameHandling.Auto within the Json.NET serialization settings. When this property is configured to automatically include type information during serialization, it allows attackers to inject malicious type names that can be executed during the deserialization process. This configuration creates a path for remote code execution attacks, as the deserialization process will attempt to load and execute the specified types from the attacker-controlled payload. The vulnerability specifically affects the platform's ability to securely handle serialized data from external sources, including user inputs, configuration files, and API responses that may contain maliciously crafted serialized objects.
The operational impact of CVE-2020-20136 extends beyond simple privilege escalation to encompass full system compromise and data exfiltration capabilities. Attackers exploiting this vulnerability can execute arbitrary code on systems running affected QuantConnect Lean versions, potentially leading to complete system takeover, data theft, and disruption of trading operations. The vulnerability is particularly concerning in quantitative finance environments where these platforms are used for algorithmic trading, backtesting, and portfolio management, as compromised systems could result in significant financial losses and regulatory compliance violations. The attack surface includes any component within the QuantConnect ecosystem that processes external serialized data, making the impact widespread across the platform's functionality.
Mitigation strategies for CVE-2020-20136 focus on correcting the insecure serialization configuration and implementing comprehensive security controls. The primary fix involves setting the TypeNameHandling property to TypeNameHandling.None or TypeNameHandling.Disallow within Json.NET configuration to prevent automatic type name inclusion during serialization. Organizations should also implement proper input validation and sanitization for all serialized data, employ secure coding practices for serialization operations, and consider implementing additional security layers such as network segmentation and monitoring solutions. This vulnerability aligns with CWE-502 which specifically addresses deserialization of untrusted data, and maps to ATT&CK technique T1059.007 for execution through serialized objects, emphasizing the need for robust security controls in serialization frameworks. System administrators should immediately upgrade to QuantConnect Lean versions 2.4.0.2 and later, which contain the necessary patches to address this vulnerability.