CVE-2016-3728 in Foreman
Summary
by MITRE
Eval injection vulnerability in tftp_api.rb in the TFTP module in the Smart-Proxy in Foreman before 1.10.4 and 1.11.x before 1.11.2 allows remote attackers to execute arbitrary code via the PXE template type portion of the PATH_INFO to tftp/.
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Analysis
by VulDB Data Team • 08/21/2022
The CVE-2016-3728 vulnerability represents a critical server-side evaluation injection flaw within the TFTP module of Foreman's Smart-Proxy component. This vulnerability exists in the tftp_api.rb file where the application fails to properly sanitize user input received through the PATH_INFO parameter during PXE template type processing. The flaw allows remote attackers to inject malicious code that gets evaluated by the server, creating a path for arbitrary code execution. The vulnerability affects Foreman versions prior to 1.10.4 and all 1.11.x versions before 1.11.2, indicating a widespread impact across multiple release branches of the popular systems management platform.
The technical implementation of this vulnerability stems from improper input validation and sanitization within the TFTP module's API handling. When a remote attacker sends a crafted request containing malicious code within the PXE template type portion of the PATH_INFO parameter, the application processes this input without adequate sanitization mechanisms. This creates an environment where the server's evaluation engine executes the injected code as part of its normal processing flow. The vulnerability specifically targets the tftp_api.rb component which handles TFTP requests for PXE boot configurations, making it particularly dangerous for network infrastructure management systems.
The operational impact of this vulnerability is severe and multifaceted. Remote attackers can leverage this flaw to execute arbitrary code on the affected Foreman server with the privileges of the web application user. This could lead to complete system compromise, data exfiltration, or the deployment of persistent backdoors. The vulnerability is particularly concerning because TFTP servers are commonly used for network boot processes, making the attack vector accessible to anyone who can reach the affected server. Security implications extend beyond immediate code execution to include potential lateral movement within networks where Foreman serves as a central management point for multiple systems.
This vulnerability aligns with CWE-94, which defines weaknesses related to improper control of generation of code, and specifically maps to the category of Server-Side Code Injection. From an attack perspective, it follows patterns consistent with the ATT&CK technique T1059.007 for Command and Scripting Interpreter: PowerShell, though the actual implementation uses Ruby evaluation mechanisms. The vulnerability demonstrates a classic lack of input sanitization and proper parameter handling that has been documented across numerous security frameworks. Organizations using Foreman systems should prioritize immediate patching and implement network segmentation to limit exposure. Additional mitigations include monitoring for suspicious TFTP requests and implementing web application firewalls to detect and block malformed PATH_INFO parameters. The vulnerability underscores the importance of secure coding practices in network infrastructure management tools where input validation and code execution contexts intersect.