CVE-2020-16248 Scanner

Prometheus Blackbox Exporter is a tool used by developers and system administrators for monitoring and probing external services to assess their availability and performance. It's designed to support a variety of protocols, including HTTP, TCP, ICMP, and more, allowing for comprehensive insight into the health of IT infrastructure. Prometheus, an open-source monitoring system, relies on exporters like Blackbox to gather metrics from different sources and present them in accessible formats. In many organizations, Prometheus and its exporters are critical components of the monitoring stack, enabling real-time tracking of service health. As IT environments grow in complexity, tools like Blackbox Exporter are integral in maintaining operational integrity and preventing downtime. Ensuring the security and reliability of such tools is paramount for organizations to safeguard their internal and external services.

The identified vulnerability in the Prometheus Blackbox Exporter pertains to a Server-Side Request Forgery (SSRF), which is caused by unsanitized input within the target parameter of the /probe endpoint. SSRF vulnerabilities allow attackers to craft requests from the server itself, potentially accessing internal services that should not be exposed to external actors. This specific vulnerability was present in versions through 0.17.0, making the environment susceptible to unauthorized access attempts. With SSRF, attackers can manipulate server requests to bypass firewall restrictions, leading to potential information leaks or further attack vectors. Addressing SSRF vulnerabilities is crucial as they can serve as entry points for attackers to gain deeper access into networked environments. Failure to patch such vulnerabilities can have significant security implications for the operational health of monitored environments.

The technical details of this vulnerability involve the exploitation of the /probe endpoint through the target parameter, which allows attackers to inject malicious URLs. By using this endpoint, an attacker can direct the server to interact with arbitrary domains. The parameter lacks sufficient validation checks to sanitize input, enabling an exploit to achieve SSRF. This weakness exposes the infrastructure to potentially malicious requests that could facilitate internal reconnaissance or other harmful actions. The interplay between the vulnerable parameter and the underlying HTTP requests forms the core of the exploit strategy. Intercepting or analyzing server responses from these crafted requests can provide attackers with insights into internal network configurations and available services.

If exploited, the SSRF vulnerability posed by this issue can lead malicious agents to conduct unauthorized scans or interactions with internal services. Through this exploitation, an attacker could potentially access confidential data, manipulate service configurations, or further exploit vulnerabilities within the internal network. The extended impact may include disruption of service availability or manipulation of service data, which could lead to broader implications for service integrity. Moreover, the reconnaissance potential of SSRF may provide critical insights for attackers planning more sophisticated attacks on the network. Addressing SSRF vulnerabilities proactively is essential to prevent these potential consequences.

REFERENCES

• https://github.com/prometheus/blackbox_exporter/issues/669
• https://nvd.nist.gov/vuln/detail/CVE-2020-16248
• https://prometheus.io/docs/operating/security/#exporters
• https://www.openwall.com/lists/oss-security/2020/08/08/3