CVE-2018-1000090 in Textpattern
Summary
by MITRE
textpattern version version 4.6.2 contains a XML Injection vulnerability in Import XML feature that can result in Denial of service in context to the web server by exhausting server memory resources. This attack appear to be exploitable via Uploading a specially crafted XML file.
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Analysis
by VulDB Data Team • 02/21/2023
The vulnerability identified as CVE-2018-1000090 affects Textpattern version 4.6.2 and represents a critical XML injection flaw within the Import XML feature. This vulnerability stems from insufficient input validation and sanitization when processing XML data, creating a pathway for malicious actors to manipulate the application's XML parser. The flaw specifically manifests during the import process where the system fails to properly handle malformed or specially crafted XML structures that could trigger unexpected behavior in the underlying XML processing libraries.
The technical implementation of this vulnerability allows attackers to construct malicious XML files that, when uploaded and processed through the import functionality, can cause the web server to consume excessive memory resources. This occurs because the XML parser does not adequately enforce resource limits or implement proper parsing constraints that would prevent maliciously constructed documents from triggering memory exhaustion conditions. The vulnerability operates at the application layer and can be exploited through simple file upload mechanisms, making it particularly dangerous as it requires minimal privileges to execute.
From an operational perspective, the impact of this vulnerability extends beyond simple denial of service to potentially compromising the entire web server infrastructure. When exploited, the memory exhaustion attack can cause the web server process to crash, leading to complete service unavailability for legitimate users. The vulnerability's exploitability via file upload means that even users with limited privileges can potentially disrupt services, making it a significant concern for organizations relying on Textpattern for content management. This type of attack aligns with the attack pattern described in the MITRE ATT&CK framework under the 'Resource Exhaustion' technique category, specifically targeting application-level resource consumption.
The vulnerability's classification under CWE-776 indicates it involves improper restriction of XML external entity references, which is a well-documented weakness in XML processing implementations. This weakness allows attackers to manipulate how XML parsers handle external entities, potentially leading to resource exhaustion through recursive entity expansion or by triggering memory-intensive parsing operations. Organizations using Textpattern version 4.6.2 should immediately implement mitigations including input validation, XML parser configuration restrictions, and resource limiting measures to prevent exploitation. The recommended approach includes upgrading to a patched version of Textpattern, implementing proper XML schema validation, and configuring web server resource limits to prevent memory exhaustion attacks. Additionally, administrators should consider implementing network-level restrictions on file upload capabilities and monitoring for suspicious XML file uploads to detect potential exploitation attempts.