CVE-2020-28360 in private-ip
Summary
by MITRE • 11/24/2020
Insufficient RegEx in private-ip npm package v1.0.5 and below insufficiently filters reserved IP ranges resulting in indeterminate SSRF. An attacker can perform a large range of requests to ARIN reserved IP ranges, resulting in an indeterminable number of critical attack vectors, allowing remote attackers to request server-side resources or potentially execute arbitrary code through various SSRF techniques.
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Analysis
by VulDB Data Team • 12/10/2020
The CVE-2020-28360 vulnerability resides within the private-ip npm package version 1.0.5 and earlier, representing a critical security flaw that undermines network boundary controls through inadequate regular expression filtering. This package, designed to identify private IP addresses, fails to properly validate and filter reserved IP ranges, creating a pathway for attackers to bypass intended security restrictions. The vulnerability specifically targets the regular expression implementation that should have been enforcing strict boundaries around private IP address spaces, allowing malicious actors to exploit the insufficient validation mechanisms. The flaw manifests when the package processes IP address inputs that fall within ARIN reserved ranges, which include critical network segments that should remain isolated from external access. This inadequacy creates a dangerous scenario where network security controls can be circumvented through seemingly benign input validation processes.
The technical implementation of this vulnerability stems from the improper construction of regular expressions within the private-ip package, which fails to account for the full spectrum of reserved IP address ranges defined by ARIN and other regional internet registries. The flawed regex pattern does not adequately distinguish between legitimate private IP addresses and potentially dangerous reserved ranges, allowing attackers to inject IP addresses that appear valid but actually fall within critical network segments. This weakness enables what is known as Server-Side Request Forgery, where an attacker can manipulate the package's validation logic to make requests to internal systems that should normally be inaccessible. The vulnerability operates at the input sanitization layer, where the package's filtering mechanism becomes a point of ingress for malicious network requests that can target various internal services. The indeterminate nature of the attack surface arises because the flawed validation allows access to multiple ARIN reserved ranges simultaneously, each potentially hosting critical network infrastructure components.
The operational impact of this vulnerability extends far beyond simple network reconnaissance, as it provides attackers with the capability to perform extensive server-side resource enumeration and potentially execute arbitrary code through various SSRF techniques. Attackers can leverage this vulnerability to probe internal network segments, access sensitive services that should remain isolated, and potentially escalate privileges through information disclosure or service manipulation. The attack surface becomes particularly dangerous because it can target multiple critical network ranges simultaneously, making traditional network segmentation controls ineffective. The vulnerability's potential for remote code execution emerges through the ability to manipulate internal service endpoints, which may be configured with weak authentication or exposed to unauthenticated access. This flaw essentially undermines the fundamental principle of network isolation by allowing external attackers to make requests to internal resources that should remain protected behind firewalls and access controls. The indeterminate nature of the attack vectors makes this vulnerability particularly challenging to defend against, as defenders cannot easily predict or enumerate all potential targets within the expanded attack surface.
Mitigation strategies for CVE-2020-28360 require immediate package updates to versions that properly implement regular expression filtering for reserved IP ranges, with particular attention to compliance with industry standards such as CWE-185 for improper regular expression handling. Organizations should implement comprehensive input validation at multiple layers, ensuring that network boundary controls are not bypassed through package-level vulnerabilities. The remediation process must include thorough code reviews of dependency packages, particularly those handling network input validation, and implementation of more robust regex patterns that correctly identify and reject all reserved IP ranges. Additionally, network segmentation controls should be reinforced through firewall rules and access control lists that limit outbound connections from applications using vulnerable packages. Security teams should also implement monitoring for unusual outbound network requests that might indicate exploitation attempts, as this vulnerability can enable attackers to perform extensive reconnaissance and potentially gain access to critical internal resources. The incident underscores the importance of dependency management and the need for continuous security assessment of third-party packages within application environments.