CVE-2018-15895 in iCMS
Summary
by MITRE
An SSRF vulnerability was discovered in idreamsoft iCMS 7.0.11 because the remote function in app/spider/spider_tools.class.php does not block DNS hostnames associated with private and reserved IP addresses, as demonstrated by 127.0.0.1 in an A record. NOTE: this vulnerability exists because of an incomplete fix for CVE-2018-14858.
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Analysis
by VulDB Data Team • 05/04/2023
The CVE-2018-15895 vulnerability represents a critical server-side request forgery flaw in the idreamsoft iCMS 7.0.11 content management system that stems from inadequate input validation mechanisms. This vulnerability specifically affects the remote function within the app/spider/spider_tools.class.php file, where the application fails to properly sanitize DNS hostname resolutions that could potentially resolve to private or reserved IP address ranges. The flaw demonstrates a clear lack of proper network boundary enforcement and hostname validation, allowing malicious actors to bypass intended security controls through DNS resolution manipulation. The vulnerability is particularly concerning because it directly enables attackers to make unauthorized requests to internal network resources that would normally be restricted from external access.
The technical implementation of this vulnerability exploits the fundamental weakness in the application's network communication handling where DNS lookups are performed without proper validation of the resulting IP addresses. When the remote function processes a hostname, it accepts DNS resolution results without checking whether the resolved IP address falls within private address ranges such as 127.0.0.1, 10.x.x.x, 172.16.x.x through 172.31.x.x, or 192.168.x.x. This oversight creates an attack vector where an attacker can manipulate DNS records to point to internal services and then leverage the application's spider functionality to access these otherwise protected resources. The vulnerability specifically manifests when an attacker can control or influence DNS resolution to return an IP address within the private range, effectively allowing the application to make requests to internal systems that should remain isolated from external network access.
This vulnerability's operational impact is significant and can lead to various security consequences including internal network reconnaissance, unauthorized access to internal services, data exfiltration, and potential lateral movement within the network infrastructure. Attackers can use this flaw to discover and exploit internal services that are not exposed to the internet, potentially gaining access to databases, administrative interfaces, or other sensitive internal systems. The vulnerability also enables more sophisticated attacks such as internal port scanning, service enumeration, and even potential exploitation of vulnerabilities in internal services that are not directly exposed to external networks. From an attacker's perspective, this represents a powerful primitive for gaining deeper access to the target environment, as it effectively bypasses network-level firewalls and access controls that are typically designed to protect internal resources.
The vulnerability's relationship to CVE-2018-14858 demonstrates a pattern of incomplete remediation where previous fixes failed to address all potential attack vectors within the same codebase. This suggests a broader architectural weakness in the application's security implementation, particularly in how it handles network communications and external resource access. Organizations should consider this vulnerability in the context of CWE-918, which specifically addresses server-side request forgery vulnerabilities where applications fail to properly validate and restrict access to external resources. The ATT&CK framework categorizes this type of vulnerability under T1071.004 for application layer protocols and T1011.001 for exfiltration via external connections, indicating both the network communication and data exfiltration aspects of the threat. The remediation approach should include implementing comprehensive DNS validation, IP address range filtering, and proper network segmentation controls to prevent unauthorized access to internal resources through application-level interfaces.
Mitigation strategies should focus on implementing strict hostname validation mechanisms that prevent resolution of private and reserved IP address ranges, establishing proper network isolation for application components, and deploying comprehensive monitoring solutions to detect unusual network activity patterns. Organizations should also consider implementing DNS sinkhole configurations for known malicious domains, deploying web application firewalls with SSRF protection capabilities, and ensuring that all network communications are properly authenticated and authorized. The fix should involve complete input validation at multiple layers, including DNS resolution validation, IP address range checking, and proper error handling for invalid network requests. Additionally, regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other application components that may be susceptible to similar attack patterns.