CVE-2004-0632 in Acrobat
Summary
by MITRE
Adobe Reader 6.0 does not properly handle null characters when splitting a filename path into components, which allows remote attackers to execute arbitrary code via a file with a long extension that is not normally handled by Reader, triggering a buffer overflow.
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Analysis
by VulDB Data Team • 07/12/2025
Adobe Reader 6.0 contains a critical buffer overflow vulnerability that stems from improper handling of null characters during filename path processing. This flaw exists in the file parsing component where the application fails to correctly validate and sanitize file extensions that contain null terminators. When processing a maliciously crafted file with an extended extension containing null bytes, the application's path splitting algorithm incorrectly interprets the null characters as legitimate path separators, leading to improper memory allocation and subsequent buffer overflow conditions. The vulnerability specifically affects the handling of file extensions that exceed normal processing limits, creating a scenario where attacker-controlled data can overwrite adjacent memory regions. This issue falls under the CWE-121 buffer overflow category, where insufficient bounds checking allows attackers to overwrite memory and potentially execute arbitrary code. The vulnerability is particularly dangerous because it can be triggered through remote exploitation, requiring no local privileges or user interaction beyond opening the malicious file. Attackers can craft files with extensions that, when processed by Reader 6.0, cause the application to allocate insufficient buffer space for the path components, resulting in memory corruption. This vulnerability aligns with ATT&CK technique T1203 by enabling arbitrary code execution through software exploitation, and represents a classic example of improper input validation that has been consistently documented in security literature as a primary attack vector. The buffer overflow occurs in the file parsing module where path components are split using null character delimiters without proper validation of the extension length, creating a predictable memory layout that attackers can exploit. The impact extends beyond simple code execution to potentially allow privilege escalation or system compromise, depending on the execution environment and user permissions. This vulnerability demonstrates the importance of robust input sanitization and proper memory management in document processing applications, particularly those handling untrusted file inputs. Security practitioners should note that this vulnerability represents a fundamental flaw in the application's file handling architecture that requires immediate remediation through patching or application hardening measures. The flaw is particularly concerning in enterprise environments where Adobe Reader is widely deployed, as it provides a straightforward path for remote attackers to compromise systems through malicious document delivery.
The technical implementation of this vulnerability involves the application's failure to properly validate the length and content of file extensions during path parsing operations. When a file with a long extension containing null characters is processed, the Reader application's internal buffer management routines allocate memory based on incorrect assumptions about the extension length. This misallocation results in a classic stack-based buffer overflow where the null characters serve as delimiters that confuse the path splitting logic. The vulnerability is exacerbated by the fact that Adobe Reader 6.0 does not implement proper bounds checking or input sanitization for file extension processing, allowing attacker-controlled data to flow directly into memory allocation routines. This type of vulnerability is categorized under CWE-129 as improper validation of input length, and represents a common pattern in legacy software where security considerations were not adequately addressed during initial development phases. The exploitation mechanism relies on the attacker crafting a file with an extension that, when processed, causes the application to overflow a buffer that contains the file path components. The overflow can be triggered through various methods including HTTP downloads, email attachments, or network file shares, making it a particularly attractive target for remote attackers. This vulnerability is also classified under ATT&CK tactic TA0002 as exploitation of software vulnerabilities, specifically targeting the execution and privilege escalation capabilities of the affected system. The memory corruption that results from this buffer overflow can be leveraged to inject and execute malicious code within the context of the Adobe Reader process, potentially leading to full system compromise.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term architectural improvements in file processing applications. The most effective immediate solution involves applying the official security patches released by Adobe for Adobe Reader 6.0, which correct the buffer overflow handling in the file parsing component. Organizations should also implement network segmentation and access controls to limit exposure to potentially malicious file types, particularly those that might trigger this vulnerability. Security monitoring should include detection of unusual file extension patterns or large file size anomalies that could indicate attempts to exploit this vulnerability. The vulnerability demonstrates the critical importance of input validation and proper memory management in security-critical applications, particularly those handling untrusted content. System administrators should consider implementing application whitelisting policies that restrict the execution of potentially vulnerable applications or enforce stricter file validation mechanisms. Additionally, organizations should conduct regular vulnerability assessments to identify similar flaws in other legacy applications that may be susceptible to similar buffer overflow attacks. The underlying architectural issues that enable this vulnerability highlight the need for comprehensive security design principles that incorporate proper bounds checking, input sanitization, and memory management practices from the initial development phases. This vulnerability serves as a reminder of the ongoing need for security awareness and the importance of maintaining up-to-date software deployments to protect against known exploits. The remediation process should also include user education about the risks of opening untrusted documents and the importance of keeping software updated with the latest security patches.