CVE-2019-5019 in Office Server Document Converter
Summary
by MITRE
A heap overflow vulnerability exists in the PowerPoint document conversion function of Rainbow PDF Office Server Document Converter V7.0 Pro R1 (7,0,2018,1113). While parsing Document Summary Property Set stream, the getSummaryInformation function is incorrectly checking the correlation between size and the number of properties in PropertySet packets, causing an out-of-bounds write that leads to heap corruption and consequent code execution.
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Analysis
by VulDB Data Team • 07/29/2023
The heap overflow vulnerability identified in CVE-2019-5019 affects Rainbow PDF Office Server Document Converter V7.0 Pro R1, specifically within its PowerPoint document conversion functionality. This vulnerability stems from improper validation mechanisms during the parsing of Document Summary Property Set stream data structures, creating a critical security flaw that can be exploited to execute arbitrary code on affected systems. The issue manifests when the getSummaryInformation function fails to accurately verify the relationship between the size parameter and the count of properties contained within PropertySet packets, leading to memory corruption during processing operations.
The technical flaw resides in the insufficient bounds checking mechanism that governs memory allocation and data parsing within the document conversion pipeline. When processing PowerPoint files, the converter encounters Document Summary Property Set streams that contain metadata about the document, including author information, title, and other document properties. The getSummaryInformation function attempts to parse these property sets but lacks proper validation of the correlation between the declared size of the property data and the actual number of properties present. This mismatch allows an attacker to craft malicious PowerPoint documents that, when processed by the vulnerable converter, trigger an out-of-bounds write operation. The heap corruption resulting from this overflow can be leveraged to overwrite critical memory locations, potentially enabling arbitrary code execution with the privileges of the affected service.
The operational impact of this vulnerability extends beyond simple document processing failures, as it represents a significant threat to system security and stability. Attackers can exploit this heap overflow by preparing specially crafted PowerPoint documents that, when submitted to the Rainbow PDF Office Server for conversion, trigger the vulnerable code path. The resulting heap corruption can lead to denial of service conditions, system crashes, or more critically, remote code execution capabilities that could allow attackers to gain unauthorized access to the server environment. This vulnerability particularly affects organizations that rely on automated document conversion services, as it can be exploited through unauthenticated network requests, making it a serious concern for enterprise environments where such services are exposed to external networks.
Mitigation strategies for CVE-2019-5019 should focus on immediate patching of the vulnerable software component, as well as implementing additional defensive measures to reduce attack surface and detection capabilities. Organizations should prioritize updating to the latest version of Rainbow PDF Office Server Document Converter that addresses this heap overflow vulnerability, as provided by the vendor. Network segmentation and access controls should be implemented to limit exposure of the vulnerable service to untrusted networks, while input validation measures should be strengthened to filter potentially malicious documents before they reach the conversion engine. The vulnerability aligns with CWE-121, heap-based buffer overflow, and can be mapped to ATT&CK technique T1059.007 for command and scripting interpreter, as successful exploitation could enable attackers to execute arbitrary commands on the compromised system. Additionally, implementing application whitelisting controls and monitoring for anomalous document processing patterns can help detect potential exploitation attempts and provide early warning capabilities against this specific vulnerability.