CVE-2016-6639 in Cloud Foundry Elastic Runtime
Summary
by MITRE
Cloud Foundry PHP Buildpack (aka php-buildpack) before 4.3.18 and PHP Buildpack Cf-release before 242, as used in Pivotal Cloud Foundry (PCF) Elastic Runtime before 1.6.38 and 1.7.x before 1.7.19 and other products, place the .profile file in the htdocs directory, which might allow remote attackers to obtain sensitive information via an HTTP GET request for this file.
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Analysis
by VulDB Data Team • 09/19/2022
The vulnerability identified as CVE-2016-6639 affects the Cloud Foundry PHP Buildpack and its associated releases, specifically versions prior to 4.3.18 and 242 respectively. This issue resides within the Pivotal Cloud Foundry Elastic Runtime ecosystem where the buildpack component incorrectly places sensitive configuration files in publicly accessible directories. The .profile file contains critical runtime information that should remain protected from unauthorized access, yet the flawed implementation exposes this file in the htdocs directory structure where it becomes accessible via standard HTTP requests. This misconfiguration represents a significant security flaw that directly violates the principle of least privilege and proper information hiding mechanisms.
The technical exploitation of this vulnerability occurs through simple HTTP GET requests targeting the .profile file located in the htdocs directory. When attackers access this file through standard web protocols, they can retrieve sensitive information including environment variables, configuration settings, and potentially authentication credentials that were intended to remain secure within the application's runtime environment. The vulnerability stems from improper file placement and access control mechanisms within the buildpack's deployment process, where the .profile file which typically contains sensitive runtime configuration data is not properly secured or restricted from public web access. This flaw falls under the CWE-200 category of Information Exposure and specifically relates to CWE-542 which addresses Information Exposure Through Directory Listing.
The operational impact of this vulnerability extends beyond simple information disclosure, as the exposed .profile file may contain database connection strings, API keys, and other credentials that could enable attackers to escalate their privileges within the Cloud Foundry environment. Attackers could leverage this information to gain unauthorized access to backend databases, service endpoints, or other interconnected systems that rely on the credentials stored in the profile file. The vulnerability affects multiple versions of Pivotal Cloud Foundry Elastic Runtime including versions before 1.6.38 and 1.7.x before 1.7.19, indicating a widespread exposure across various deployment configurations. This issue aligns with ATT&CK technique T1083 (File and Directory Discovery) and T1552 (Unsecured Credentials) as attackers can systematically discover and extract sensitive information from exposed configuration files.
Organizations utilizing affected versions of Cloud Foundry should immediately implement mitigations including updating to patched versions of the PHP Buildpack and Elastic Runtime releases, implementing proper file access controls, and conducting comprehensive security reviews of all buildpack configurations. The recommended remediation involves ensuring that sensitive files like .profile are not placed in publicly accessible web directories and that proper access controls are enforced through web server configurations or application-level security measures. Security teams should also implement monitoring solutions to detect unauthorized access attempts to sensitive files and establish automated scanning processes to identify similar misconfigurations across their Cloud Foundry deployments. Additionally, regular security training for development teams on secure configuration practices and proper file handling within containerized environments should be implemented to prevent similar vulnerabilities from occurring in future deployments.