CVE-2021-34066 in Developer
Summary
by MITRE • 08/31/2021
An issue was discovered in EdgeGallery/developer before v1.0. There is a "Deserialization of yaml file" vulnerability that can allow attackers to execute system command through uploading the malicious constructed YAML file.
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Analysis
by VulDB Data Team • 09/03/2021
The vulnerability identified as CVE-2021-34066 resides within the EdgeGallery/developer platform prior to version 1.0, representing a critical security flaw in the application's handling of YAML file processing. This issue falls under the broader category of insecure deserialization vulnerabilities, where the system fails to properly validate and sanitize user-supplied YAML content before processing it. The vulnerability stems from the application's insecure deserialization mechanism that directly interprets and executes YAML payloads without adequate input sanitization or access controls. Attackers can exploit this weakness by crafting malicious YAML files that contain serialized objects or commands designed to be executed when the system processes the uploaded content. The vulnerability is particularly dangerous because it allows for arbitrary command execution on the target system, enabling attackers to gain unauthorized access to underlying resources and potentially escalate their privileges. This flaw represents a significant risk to organizations using the EdgeGallery/developer platform, as it provides a direct pathway for remote code execution through seemingly benign file upload operations.
The technical implementation of this vulnerability demonstrates a classic deserialization attack vector where the YAML parser does not properly validate the structure or content of the uploaded files. When a user uploads a malicious YAML file, the application's deserialization process treats the content as executable code rather than mere data, leading to arbitrary command execution on the server. The vulnerability is classified as CWE-502, which specifically addresses deserialization of untrusted data, and aligns with ATT&CK technique T1059.001 for command and script injection. This weakness allows attackers to bypass normal access controls and execute arbitrary commands with the privileges of the application process, potentially leading to complete system compromise. The lack of proper input validation and sanitization creates an environment where attackers can inject malicious payloads that are automatically executed during the YAML processing phase, making the vulnerability particularly stealthy and dangerous.
The operational impact of CVE-2021-34066 extends beyond simple command execution, as it provides attackers with a powerful foothold for further exploitation within the targeted environment. Once an attacker successfully uploads a malicious YAML file, they can leverage the executed commands to establish persistent access, escalate privileges, or launch additional attacks against networked systems. The vulnerability affects the EdgeGallery/developer platform's file upload functionality, making it a prime target for attackers seeking to compromise the application's integrity and availability. Organizations using affected versions face significant risk of data breaches, system compromise, and potential regulatory violations due to the exposure of sensitive information through unauthorized access. The vulnerability's impact is amplified by the fact that it can be exploited remotely without requiring authentication, making it particularly attractive to threat actors seeking low-effort, high-impact attacks. The compromised system may also serve as a launchpad for lateral movement within the network, allowing attackers to expand their access beyond the initial compromised system.
Mitigation strategies for CVE-2021-34066 must address both the immediate vulnerability and broader security posture of the affected system. The most effective approach involves upgrading to EdgeGallery/developer version 1.0 or later, which contains the necessary security patches to prevent unauthorized YAML deserialization. Organizations should implement strict input validation and sanitization for all file uploads, particularly those involving structured data formats like YAML. The application should employ secure deserialization practices that either avoid deserializing untrusted data entirely or implement proper security controls such as object whitelisting and access restrictions. Network-level controls including web application firewalls and intrusion detection systems can help detect and block malicious YAML file uploads. Additionally, implementing principle of least privilege access controls and regular security audits will help minimize the potential impact should the vulnerability be exploited. Security teams should also consider implementing file type restrictions and content scanning for uploaded YAML files to prevent execution of malicious payloads. The remediation process should include comprehensive testing to ensure that the patch does not introduce regressions in legitimate functionality while maintaining the security improvements necessary to protect against this specific deserialization vulnerability.