CVE-2020-13166 in MyLittleAdmin
Summary
by MITRE
The management tool in MyLittleAdmin 3.8 allows remote attackers to execute arbitrary code because machineKey is hardcoded (the same for all customers' installations) in web.config, and can be used to send serialized ASP code.
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Analysis
by VulDB Data Team • 04/05/2025
The vulnerability identified as CVE-2020-13166 resides within the management tool of MyLittleAdmin version 3.8, representing a critical security flaw that enables remote code execution through improper cryptographic implementation. This issue stems from a hardcoded machineKey value within the web.config configuration file that is consistently used across all customer installations, creating a universal decryption key that attackers can exploit to manipulate serialized ASP.NET data. The flaw fundamentally compromises the application's security model by eliminating the cryptographic randomness necessary to protect serialized objects from tampering.
The technical implementation of this vulnerability leverages the predictable nature of the hardcoded machineKey to perform malicious deserialization attacks against the ASP.NET application framework. When the management tool processes serialized data, it relies on the machineKey for validation and decryption purposes, but since this key remains constant across all deployments, attackers can craft specially formatted serialized objects that, when processed by the vulnerable application, execute arbitrary code with the privileges of the web application pool. This represents a classic example of insecure deserialization where the lack of proper cryptographic protection enables attackers to manipulate serialized data streams. The vulnerability aligns with CWE-327, which addresses the use of weak or predictable cryptographic keys, and specifically demonstrates how hardcoded cryptographic values can completely undermine application security.
From an operational perspective, this vulnerability creates a severe risk landscape for organizations using MyLittleAdmin 3.8, as it provides attackers with a straightforward path to remote code execution without requiring any authentication or additional attack vectors. The impact extends beyond simple code execution to include potential full system compromise, data exfiltration, and lateral movement within network environments. Attackers can leverage this vulnerability to establish persistent access, deploy additional malicious tools, or use the compromised system as a launch point for broader network attacks. The vulnerability's exploitation potential is amplified by the fact that it affects all installations using the same software version, making it particularly attractive to automated attack frameworks. This aligns with ATT&CK technique T1059.001 for command and scripting interpreter, where attackers can execute malicious code through the deserialization mechanism.
Organizations should immediately implement mitigations including updating to a patched version of MyLittleAdmin that generates unique machineKey values for each installation, implementing proper cryptographic key management practices, and monitoring for suspicious serialized data processing activities. The recommended approach involves generating new machineKey values with strong randomization for each deployment, implementing proper input validation for serialized objects, and establishing network segmentation to limit the potential impact of successful exploitation. Additionally, organizations should consider implementing application whitelisting policies and monitoring for unusual deserialization patterns that might indicate exploitation attempts. The vulnerability serves as a critical reminder of the importance of cryptographic key management practices and the dangers of hardcoding security parameters in production applications, emphasizing the need for proper security testing and configuration reviews to prevent similar issues in other software components.