CVE-2017-16035 in hubl-server
Summary
by MITRE
The hubl-server module is a wrapper for the HubL Development Server. During installation hubl-server downloads a set of dependencies from api.hubapi.com. It appears in the code that these files are downloaded over HTTPS however the api.hubapi.com endpoint redirects to a HTTP url. Because of this behavior an attacker with the ability to man-in-the-middle a developer or system performing a package installation could compromise the integrity of the installation.
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Analysis
by VulDB Data Team • 02/14/2020
The vulnerability identified as CVE-2017-16035 resides within the hubl-server module, which serves as a development server wrapper for HubL (HubSpot Language) template processing. This module operates as a critical component in the HubSpot development ecosystem, facilitating local development and testing of HubSpot templates and scripts. The security flaw manifests during the module's installation process when it attempts to fetch dependencies from the legitimate api.hubapi.com endpoint. While the initial download request appears to use secure HTTPS protocols, the api.hubapi.com server exhibits a problematic redirect behavior that ultimately channels the dependency downloads through unencrypted HTTP connections. This redirect mechanism represents a fundamental security weakness that directly violates the principle of secure communication channels, as outlined in security standards such as CWE-200 and CWE-319. The vulnerability creates an exploitable condition where network attackers positioned between the installing system and the HubSpot API can intercept and modify the downloaded dependencies during transit.
The technical implementation of this vulnerability stems from improper handling of HTTP redirects within the installation process. When the hubl-server module initiates its dependency download sequence, it establishes an HTTPS connection to api.hubapi.com but fails to validate or enforce the security of the subsequent redirect chain. This behavior creates a downgrade attack vector where the originally secure HTTPS connection is effectively compromised by the subsequent HTTP redirection. The flaw specifically aligns with CWE-319, which addresses the exposure of sensitive information through improper handling of HTTP redirects, and CWE-200, which covers the improper handling of information exposure. The vulnerability is particularly concerning because it affects the integrity of the entire installation process, potentially allowing attackers to inject malicious code into the downloaded dependencies that would then execute during normal development operations.
The operational impact of CVE-2017-16035 extends beyond simple information disclosure to represent a serious supply chain compromise risk. When developers install or update the hubl-server module, they unknowingly accept the risk that their development environment may become compromised through the installation of modified dependencies. This vulnerability directly enables the attack pattern described in MITRE ATT&CK technique T1133, which covers external remote services and specifically targets the manipulation of software supply chains. The compromised dependencies could contain malicious code that executes during local development, potentially leading to unauthorized access to development environments, data exfiltration, or further exploitation of the development infrastructure. Additionally, since this vulnerability affects the installation process rather than runtime operations, the attack surface is expanded to include all developers and systems that might install or update the affected module, making it particularly dangerous in enterprise development environments.
Mitigation strategies for CVE-2017-16035 should focus on both immediate remediation and long-term architectural improvements. The most effective immediate solution involves updating the hubl-server module to properly handle HTTP redirects by either enforcing HTTPS throughout the entire download chain or implementing certificate pinning for the api.hubapi.com endpoint. Organizations should also consider implementing network monitoring to detect and prevent unauthorized redirects from HTTPS to HTTP connections. From a broader security perspective, this vulnerability highlights the importance of implementing secure dependency management practices as outlined in industry standards such as the OWASP Dependency Check framework and the NIST SP 800-161 guidelines for secure software development. System administrators should also consider using secure package managers that implement integrity checks and verification mechanisms for all downloaded dependencies, while developers should be trained to recognize and avoid installing software from untrusted sources that might exhibit similar redirect behaviors. The vulnerability serves as a reminder that even seemingly minor implementation details in secure communication protocols can create significant security risks in software supply chain processes.