CVE-2018-1000548 in Umlet
Summary
by MITRE
Umlet version < 14.3 contains a XML External Entity (XXE) vulnerability in File parsing that can result in disclosure of confidential data, denial of service, server side request forgery. This attack appear to be exploitable via Specially crafted UXF file. This vulnerability appears to have been fixed in 14.3.
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Analysis
by VulDB Data Team • 03/29/2023
The vulnerability identified as CVE-2018-1000548 represents a critical XML External Entity (XXE) flaw discovered in Umlet versions prior to 14.3. This vulnerability specifically affects the file parsing functionality within the Umlet application, which is widely used for creating UML diagrams and other visual modeling tools. The XXE vulnerability arises from the application's improper handling of XML input when processing UXF (Umlet eXtensible Format) files, which are the native file format used by Umlet for storing diagram data.
The technical implementation of this vulnerability stems from the application's XML parser not properly sanitizing external entity references during file processing. When a specially crafted UXF file is opened, the parser attempts to resolve external entities that may point to internal network resources, local files, or external servers. This behavior creates multiple attack vectors including confidential data disclosure through file read operations, denial of service via resource exhaustion attacks, and server-side request forgery that can be leveraged to access internal systems. The vulnerability is particularly concerning because UXF files are commonly shared and opened within collaborative environments, making exploitation potentially widespread.
From an operational perspective, this vulnerability poses significant risks to organizations using Umlet for diagram creation and sharing. Attackers can craft malicious UXF files that, when opened by unsuspecting users, can exfiltrate sensitive data from the local system or internal network resources. The server-side request forgery component allows attackers to potentially bypass network security controls and access systems that would normally be restricted. This vulnerability aligns with CWE-611 (Improper Restriction of XML External Entity Reference) and maps to ATT&CK technique T1059.007 (Command and Scripting Interpreter: Unix Shell) and T1190 (Exploit Public-Facing Application) within the enterprise attack framework. The impact extends beyond individual users to potentially compromise entire network infrastructures through lateral movement and data exfiltration.
Organizations should immediately upgrade to Umlet version 14.3 or later to remediate this vulnerability, as this represents the official fix released by the vendor. Additional mitigations include implementing strict file validation policies for UXF files, particularly in collaborative environments, and educating users about the risks of opening files from untrusted sources. Network segmentation and firewall rules can help limit potential lateral movement if exploitation occurs, while regular security audits should verify that no legacy versions remain in use. The vulnerability demonstrates the importance of proper XML parsing security practices and highlights the need for regular security updates in development and modeling tools that process external input.