CVE-2017-16024 in sync-exec
Summary
by MITRE
The sync-exec module is used to simulate child_process.execSync in node versions <0.11.9. Sync-exec uses tmp directories as a buffer before returning values. Other users on the server have read access to the tmp directory, possibly allowing an attacker on the server to obtain confidential information from the buffer/tmp file, while it exists.
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Analysis
by VulDB Data Team • 03/21/2023
The sync-exec module represents a critical security vulnerability in Node.js environments prior to version 0.11.9, where the module attempts to emulate the behavior of child_process.execSync through the use of temporary directories as data buffers. This approach introduces a fundamental flaw in the security model of the system, as the temporary directories created during execution are not properly secured against unauthorized access. The vulnerability stems from the module's reliance on system-wide temporary directories that are typically accessible to all users on the server, creating an attack surface where malicious actors can potentially intercept sensitive data that should remain confidential during process execution. The design flaw allows for information disclosure through the temporary file system, which directly violates the principle of least privilege and proper resource isolation.
The technical implementation of this vulnerability occurs when the sync-exec module creates temporary files to buffer output data from executed processes, storing this information in standard temporary directories such as /tmp or /var/tmp. These directories are configured with broad read permissions, enabling any user on the system to access the temporary files created by the module. When the module executes commands through child_process.exec, it captures the output and writes it to temporary files before returning the results to the calling process. The temporary files remain accessible to other users on the system throughout their existence, creating a window of opportunity for attackers to read sensitive information that was meant to be private within the context of the executing process. This design pattern directly corresponds to CWE-310, which addresses cryptographic issues and improper handling of sensitive data, specifically focusing on the exposure of sensitive information through insecure temporary file handling.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable attackers to obtain confidential data that might include authentication tokens, API keys, database credentials, or other sensitive information processed through the vulnerable module. An attacker with access to the system can monitor the temporary directories for files created by the sync-exec module, potentially gaining access to data that should remain protected during execution. This vulnerability can be particularly dangerous in multi-tenant environments or shared hosting scenarios where multiple users operate on the same system, as it allows for cross-user data leakage. The attack vector is relatively simple to exploit, requiring only basic file system access and knowledge of the temporary directory structure, making it a significant concern for applications that rely on the sync-exec module for process execution.
Mitigation strategies for this vulnerability should focus on both immediate remediation and long-term architectural improvements. The most effective immediate solution involves upgrading to Node.js versions 0.11.9 or later, where the native child_process.execSync function properly handles temporary data without exposing it to unauthorized users. Organizations should also implement proper temporary file management practices, including creating secure temporary directories with restricted permissions and ensuring that sensitive data is not stored in system-wide temporary locations. The implementation of proper file permissions, such as setting temporary directories to mode 700 with restricted user access, can significantly reduce the risk of information disclosure. Additionally, security monitoring should be implemented to detect unusual access patterns to temporary directories, which could indicate exploitation attempts. From an ATT&CK framework perspective, this vulnerability maps to techniques involving credential access and information gathering through insecure temporary file handling, emphasizing the need for proper privilege separation and secure coding practices in node.js applications.