CVE-2004-0629 in Acrobat
Summary
by MITRE
Buffer overflow in the ActiveX component (pdf.ocx) for Adobe Acrobat 5.0.5 and Acrobat Reader, and possibly other versions, allows remote attackers to execute arbitrary code via a URI for a PDF file with a null terminator (%00) followed by a long string.
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Analysis
by VulDB Data Team • 07/12/2025
The vulnerability described in CVE-2004-0629 represents a critical buffer overflow flaw within Adobe Acrobat 5.0.5's ActiveX component known as pdf.ocx. This component is integrated into web browsers to enable inline viewing of pdf documents, making it a prime target for remote code execution attacks. The flaw specifically manifests when processing Uniform Resource Identifiers that reference pdf files containing a null terminator character followed by an excessively long string. This particular attack vector exploits the component's inadequate input validation mechanisms, which fail to properly handle malformed uri sequences that contain embedded null bytes.
The technical implementation of this vulnerability stems from improper bounds checking within the pdf.ocx ActiveX control's string handling routines. When a malicious uri is processed, the component attempts to copy the uri string into a fixed-size buffer without sufficient validation of the input length or content. The presence of the null terminator character %00 effectively truncates the uri string at an arbitrary point, while the subsequent long string content overflows the allocated buffer space. This buffer overflow condition creates an exploitable memory corruption scenario that allows attackers to overwrite adjacent memory locations with controlled data. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, which is a well-documented weakness in software development practices that violates the principle of input sanitization and memory boundary enforcement.
The operational impact of this vulnerability extends beyond simple code execution capabilities, as it provides attackers with the ability to gain complete control over the affected system. Successful exploitation enables remote attackers to execute arbitrary code with the privileges of the user running the affected browser application, typically resulting in full system compromise. This vulnerability particularly affects users running Adobe Acrobat 5.0.5 and potentially other versions that utilize the same pdf.ocx component, making it a widespread threat across numerous installations. The attack can be delivered through various vectors including malicious web pages, email attachments, or any mechanism that triggers the automatic loading of pdf content within a vulnerable browser environment.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1203 - Exploitation for Client Execution, where adversaries leverage application vulnerabilities to execute malicious code. The attack chain typically involves initial access through a malicious website or email, followed by the exploitation of the ActiveX component to establish a foothold. Organizations should implement multiple layers of defense including browser security settings, ActiveX control restrictions, and regular patch management protocols. The recommended mitigations include immediate installation of Adobe's security patches, disabling ActiveX controls in web browsers, implementing network-based intrusion detection systems, and conducting regular vulnerability assessments. Additionally, users should be educated about the dangers of clicking on untrusted links or opening pdf files from unknown sources, as social engineering remains a common initial attack vector for exploiting such vulnerabilities.