CVE-2004-0631 in Acrobat
Summary
by MITRE
Buffer overflow in the uudecoding feature for Adobe Acrobat Reader 5.0.5 and 5.0.6 for Unix and Linux, and possibly other versions including those before 5.0.9, allows remote attackers to execute arbitrary code via a long filename for the PDF file that is provided to the uudecode command.
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Analysis
by VulDB Data Team • 03/09/2021
The vulnerability described in CVE-2004-0631 represents a critical buffer overflow condition within Adobe Acrobat Reader's uudecoding functionality on Unix and Linux systems. This security flaw specifically affects versions 5.0.5 and 5.0.6 of the software, with potential impact extending to earlier versions up to 5.0.8. The vulnerability arises from inadequate input validation during the processing of uuencoded files, creating a scenario where maliciously crafted filenames can trigger memory corruption. The uudecoding feature is commonly used to decode uuencoded attachments within PDF documents, making this flaw particularly dangerous as it can be exploited through routine document handling operations. The flaw demonstrates a classic buffer overflow pattern where insufficient bounds checking allows attackers to overwrite adjacent memory locations, potentially leading to arbitrary code execution. This vulnerability falls under the CWE-121 category of buffer overflow conditions, specifically representing a stack-based buffer overflow that can be exploited through improper handling of user-supplied data.
The technical exploitation of this vulnerability occurs when Adobe Acrobat Reader processes a PDF file containing a maliciously crafted uuencoded attachment with an excessively long filename. The uudecode command within the application fails to properly validate the length of the filename before copying it into a fixed-size buffer, resulting in memory corruption. Attackers can leverage this condition to overwrite return addresses, function pointers, or other critical memory locations, effectively taking control of the application's execution flow. The attack vector is remote, meaning that an attacker can deliver a malicious PDF file through email, web downloads, or other network-based delivery mechanisms without requiring local system access. This makes the vulnerability particularly dangerous in enterprise environments where users frequently open PDF documents from untrusted sources. The exploitation process aligns with ATT&CK technique T1203 by leveraging application vulnerabilities to gain code execution privileges, and T1068 which involves exploiting vulnerabilities in legitimate programs to execute malicious code.
The operational impact of CVE-2004-0631 extends beyond simple code execution to encompass complete system compromise when attackers successfully exploit the vulnerability. Once executed, the malicious code can perform various malicious activities including privilege escalation, data exfiltration, or establishing persistent backdoors within the affected system. The vulnerability affects not just individual user workstations but can potentially compromise entire network infrastructures if exploited at scale. Organizations using affected versions of Adobe Acrobat Reader face significant risk as the exploitation requires no special privileges beyond normal user access to open PDF documents. The vulnerability's impact is compounded by the widespread use of Adobe Acrobat Reader across enterprise environments, making it a prime target for attackers seeking to gain unauthorized access to sensitive information. System administrators must consider the potential for lateral movement within networks if exploitation occurs, as compromised systems may serve as launching points for further attacks against other network resources.
Mitigation strategies for this vulnerability focus on immediate patching of affected software versions and implementation of defensive measures to reduce attack surface. The most effective solution involves upgrading to Adobe Acrobat Reader version 5.0.9 or later, where the buffer overflow has been addressed through proper input validation and bounds checking mechanisms. Organizations should implement application whitelisting policies to restrict execution of untrusted PDF files and consider deploying sandboxing solutions to isolate PDF processing activities. Network-based defenses such as email filtering and web proxies can help prevent delivery of malicious PDF files to end users, while endpoint protection solutions should be configured to monitor for suspicious uudecoding activities. Security monitoring should include detection of unusual PDF processing patterns and potential buffer overflow indicators in system logs. Additionally, regular vulnerability assessments should be conducted to identify other potentially affected applications and systems that may share similar uudecoding functionality. The remediation process should also include user education about the dangers of opening PDF files from untrusted sources and the importance of keeping software updated to prevent exploitation of known vulnerabilities.