CVE-2009-0557 is a high-severity vulnerability that affects multiple versions of Microsoft Office, including Office 2000, XP, 2003, and various versions for Mac. This vulnerability allows remote attackers to execute arbitrary code through a crafted Excel file that contains a malformed record object. The risk to organizations includes unauthorized access and control over systems where vulnerable Office products are utilized. Given the nature of the vulnerability, it is imperative that organizations take immediate action to patch affected systems.
The vulnerability has a CVSS score of 7.8, indicating a high level of severity. This score reflects the potential impact on confidentiality, integrity, and availability, which are all rated as high. The exploitation status is notable; the vulnerability is included in the Known Exploited Vulnerabilities (KEV) catalog, meaning that it has been recognized for active exploitation in the wild. Organizations should prioritize patching immediately.
Organizations using affected Microsoft Office versions should be aware that this vulnerability can be triggered through user interaction, making it crucial to educate users about the risks associated with opening untrusted Excel files. The urgency for defenders is paramount, as attackers may leverage this vulnerability to gain unauthorized access to sensitive information.
The published date of the CVE is June 10, 2009, and the last modified date is April 22, 2026. Organizations must ensure they are running the latest security updates to mitigate the risks associated with CVE-2009-0557.
Vulnerability Details
The official description states that this vulnerability allows remote attackers to execute arbitrary code via a crafted Excel file containing a malformed record object, commonly referred to as the "Object Record Corruption Vulnerability." The affected products include Microsoft Office versions across various platforms, including Office Compatibility Pack and Office Excel Viewer. The vulnerability has been assigned CWE-94, indicating improper control of generation of code ('Code Injection').
Technical Analysis
The root cause of CVE-2009-0557 lies in the way Microsoft Office handles specific Excel file formats, leading to object record corruption. The attack vector is local, requiring user interaction to open a maliciously crafted Excel file. The attack complexity is classified as low, as no special privileges are required for exploitation. The vulnerability demands user interaction, which can lead to significant confidentiality, integrity, and availability impacts.
Risk & Impact Analysis
Real-world deployment risk associated with CVE-2009-0557 is significant, as it can lead to unauthorized access and control of compromised systems. Organizations that utilize the affected versions of Microsoft Office should assess their exposure and potential blast radius of an attack. The urgency for remediation is critical given the high CVSS score and the inclusion in the KEV catalog, indicating active exploitation in the wild.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | Yes |
Ransomware Use | No |
Affected Versions
The affected versions include Microsoft Office 2000 SP3, Office XP SP3, Office 2003 SP3, Office 2004 and 2008 for Mac, and Microsoft Office 2007 SP1 and SP2. Additionally, the Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats SP1 and SP2 is vulnerable. All versions prior to vendor patch should be considered at risk.
Mitigation & Remediation
Organizations should apply updates per vendor instructions. The relevant patch for this vulnerability can be found in Microsoft Security Bulletin MS09-021. If patching is not immediately possible, consider implementing network controls to limit exposure to untrusted Excel files. Additionally, monitoring for behavioral anomalies when users open Excel files can help identify potential exploitation attempts. For further information on effective remediation strategies, organizations should consider conducting a penetration testing engagement to assess vulnerabilities in their environment.
Detection Guidance
Monitoring for log indicators associated with the opening of Excel files can provide insights into potential exploitation. Security teams should look for behavioral anomalies, such as unexpected file types being opened or unusual access patterns. Network signatures may also be implemented to detect malicious Excel files attempting to exploit the vulnerability.
AppSecure Threat Intelligence Insight
CVE-2009-0557 reflects a long-term trend in software vulnerabilities where user interaction remains a critical factor for exploitation. Organizations must remain vigilant in their security practices, particularly in user education and awareness regarding file handling. The inclusion of this vulnerability in the KEV catalog underscores the need for ongoing monitoring and proactive security posture. For insights on vulnerability management, organizations can refer to our guide on vulnerability management programs and consider engaging in penetration testing to evaluate their defenses against similar vulnerabilities.
Known Exploitation Timeline
CVE-2009-0557 was added to the KEV catalog on June 8, 2022, indicating that it has been recognized for known exploitation.
EPSS Risk Context
The EPSS score for CVE-2009-0557 is 0.863650000, placing it in the 99.4 percentile, indicating a high likelihood of exploitation in the wild. Organizations should take this score into consideration when prioritizing their security efforts.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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