CVE-2019-17554 in Olingo
Summary
by MITRE
The XML content type entity deserializer in Apache Olingo versions 4.0.0 to 4.6.0 is not configured to deny the resolution of external entities. Request with content type "application/xml", which trigger the deserialization of entities, can be used to trigger XXE attacks.
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Analysis
by VulDB Data Team • 11/29/2024
The vulnerability identified as CVE-2019-17554 resides within Apache Olingo's XML content type entity deserializer, affecting versions ranging from 4.0.0 through 4.6.0. This flaw represents a critical security weakness that directly enables XML External Entity (XXE) attack vectors, exploiting the deserializer's inadequate configuration to prevent external entity resolution. The vulnerability specifically manifests when processing requests containing content type "application/xml" that trigger the deserialization process, creating a pathway for malicious actors to exploit the system's XML parsing functionality.
The technical implementation of this vulnerability stems from the deserializer's failure to properly configure XML parsing parameters to reject external entity references. When Apache Olingo processes XML content with the application/xml content type, it utilizes standard XML parsing libraries that, by default, may resolve external entities if not explicitly configured otherwise. This misconfiguration allows attackers to craft malicious XML payloads that reference external resources, potentially enabling data exfiltration, server-side request forgery, or denial of service conditions. The vulnerability aligns with CWE-611, which specifically addresses improper restriction of XML external entity reference, and represents a classic XXE attack scenario where the application's XML parser is not properly secured against external resource resolution.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable attackers to perform various malicious activities through the XML processing pipeline. An attacker could leverage this weakness to access internal system resources, bypass authentication mechanisms, or conduct server-side request forgery attacks by referencing external servers or files. The attack surface is particularly concerning given that Olingo is commonly used in enterprise applications and web services that process XML data, making this vulnerability potentially exploitable across numerous production environments. The vulnerability's severity is amplified by the fact that it does not require authentication or specialized privileges to exploit, as the XML parsing occurs during normal request processing.
Organizations affected by CVE-2019-17554 should immediately implement mitigations including updating to Apache Olingo versions that properly address the XXE vulnerability, typically those beyond the affected range. The recommended approach involves configuring XML parsers to disable external entity resolution through proper parameter settings such as setting the "http://apache.org/xml/features/disallow-doctype-decl" feature to true, or equivalent security configurations in the XML processing libraries. Additionally, implementing proper input validation and sanitization of XML content, along with network-level restrictions that prevent access to internal resources from the application servers, provides layered defense against exploitation attempts. Security monitoring should include detection of unusual XML processing patterns that might indicate XXE attack attempts, and regular security assessments should verify that XML parsing configurations remain secure against similar vulnerabilities. This vulnerability demonstrates the importance of proper XML security configuration and aligns with ATT&CK technique T1213.002 for data from information repositories, as it enables unauthorized access to internal system information through XML processing weaknesses.