CVE-2018-18274 in pdfalto
Summary
by MITRE
A issue was found in pdfalto 0.2. There is a heap-based buffer overflow in the TextPage::addAttributsNode function in XmlAltoOutputDev.cc.
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Analysis
by VulDB Data Team • 05/25/2023
The vulnerability identified as CVE-2018-18274 represents a critical heap-based buffer overflow flaw within the pdfalto 0.2 software suite, specifically within the TextPage::addAttributsNode function located in the XmlAltoOutputDev.cc source file. This issue arises from inadequate input validation and memory management practices during the processing of PDF documents, particularly when handling text attributes within the ALTO (ASCII Lightweight Text Objects) output format. The flaw manifests when the application processes malformed or specially crafted PDF files that contain excessive or improperly structured attribute data, leading to memory corruption that can potentially be exploited by malicious actors.
The technical nature of this vulnerability places it firmly within the scope of CWE-121, heap-based buffer overflow, which occurs when a program writes data beyond the boundaries of a heap-allocated buffer. The TextPage::addAttributsNode function appears to lack proper bounds checking mechanisms when processing attribute nodes from XML output generated during PDF text extraction. This function likely allocates a fixed-size buffer to store attribute information but fails to validate the actual size of incoming data, allowing attackers to overflow the allocated memory space and overwrite adjacent heap memory regions. The vulnerability is particularly concerning as it operates within a document processing application that may be invoked automatically during document handling workflows, potentially providing an attack surface for remote exploitation.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as heap-based buffer overflows can enable arbitrary code execution under certain conditions. When exploited successfully, this vulnerability could allow attackers to execute malicious code with the privileges of the affected application process, potentially leading to complete system compromise. The vulnerability affects pdfalto versions prior to 0.3, indicating that it represents a known issue that was subsequently patched by the developers. Organizations utilizing pdfalto for document processing, particularly in automated environments or when handling untrusted PDF content, face significant risk from this flaw. The vulnerability is especially dangerous in server environments where pdfalto might be used to process documents from external sources without proper sanitization, creating potential entry points for attackers to establish persistent access or escalate privileges.
Mitigation strategies for this vulnerability should focus on immediate patching to version 0.3 or later, which contains the necessary fixes for the buffer overflow issue. System administrators should also implement input validation measures to sanitize PDF documents before processing them through pdfalto, particularly when dealing with external or untrusted sources. Additional protective measures include running the application with restricted privileges, implementing memory protection mechanisms such as stack canaries and address space layout randomization, and monitoring for unusual memory access patterns that might indicate exploitation attempts. Organizations should also consider implementing network segmentation and access controls to limit exposure of systems running pdfalto, while maintaining regular vulnerability assessments to identify similar issues in other document processing software components. The ATT&CK framework categorizes this vulnerability under T1059.007 for execution through scripting and T1203 for exploitation of software vulnerabilities, highlighting the multi-faceted nature of potential attack vectors that could leverage this flaw.