CVE-2007-4776 in Visual Basic
Summary
by MITRE
Buffer overflow in Microsoft Visual Basic 6.0 and Enterprise Edition 6.0 SP6 allows user-assisted remote attackers to execute arbitrary code via a Visual Basic project (vbp) file containing a long Reference line, related to VBP_Open and OLE. NOTE: there are limited usage scenarios under which this would be a vulnerability.
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Analysis
by VulDB Data Team • 10/05/2024
The vulnerability described in CVE-2007-4776 represents a critical buffer overflow condition affecting Microsoft Visual Basic 6.0 and its Enterprise Edition 6.0 SP6 release. This flaw exists within the handling of Visual Basic project files with excessively long Reference lines, specifically when these files are processed through the VBP_Open and OLE components. The vulnerability operates under the Common Weakness Enumeration classification of CWE-121, which encompasses classic stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The security implications are particularly severe as this issue enables arbitrary code execution when a maliciously crafted Visual Basic project file is opened by an unsuspecting user.
The technical exploitation mechanism involves the manipulation of Visual Basic project files that contain Reference lines exceeding the allocated buffer space within the application's memory management routines. When the Visual Basic environment attempts to parse these overly long Reference entries, it fails to properly validate the input length before copying data into fixed-size buffers. This failure creates a condition where attacker-controlled data can overflow into adjacent memory regions, potentially corrupting program execution flow. The vulnerability specifically leverages the OLE (Object Linking and Embedding) infrastructure that Visual Basic uses for component integration, making it particularly dangerous as it can be triggered through legitimate file opening operations without requiring special privileges or direct system-level access. The attack vector requires user interaction since the malicious file must be opened by a victim, but once executed, the consequences can be catastrophic.
The operational impact of this vulnerability extends beyond simple code execution to encompass potential system compromise and data exfiltration capabilities. When successfully exploited, attackers can gain full control over the affected system, potentially establishing persistent backdoors or deploying additional malicious payloads. The limited usage scenarios mentioned in the original description actually reflect the specific conditions under which the vulnerability becomes exploitable, typically requiring that the victim has Visual Basic 6.0 installed and that they open a specially crafted project file. This makes the attack surface somewhat constrained but also more targeted, as it requires specific environmental conditions to be met. The vulnerability's classification under the ATT&CK framework would align with techniques involving execution through legitimate user processes and privilege escalation through application exploitation.
Mitigation strategies for CVE-2007-4776 should focus on both immediate protective measures and long-term remediation approaches. Organizations should implement strict file validation policies that prevent opening of Visual Basic project files from untrusted sources, particularly those with unusually long Reference lines. System administrators should consider disabling Visual Basic 6.0 installations on systems where they are not absolutely required, as this eliminates the attack surface entirely. Additionally, implementing application whitelisting solutions can prevent the execution of malicious Visual Basic project files even if they somehow bypass initial defenses. The most effective long-term solution involves upgrading to modern development environments that do not contain these legacy buffer overflow vulnerabilities, as Microsoft has discontinued support for Visual Basic 6.0 and its associated components. Network-based protections such as email filtering and web application firewalls should also be configured to block suspicious Visual Basic project files from reaching end users, reducing the likelihood of successful exploitation through social engineering vectors.