CVE-2011-1889
Microsoft Forefront TMG Remote Code Execution Vulnerability
Description
CVE-2011-1889 is a CRITICAL vulnerability in Microsoft Forefront Threat Management Gateway (TMG), carrying a CVSS 3.1 score of 9.8. A remote code execution vulnerability exists in the Forefront Threat Management Gateway (TMG) Firewall Client Winsock provider that could allow code execution in the security context of the client application. The flaw is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). Exploitation targets the network security gateway, which occupies a critical position in the network perimeter, making successful exploitation particularly dangerous as it can compromise the security boundary itself. This CVE is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog with a remediation deadline of 2022-03-24. With an EPSS score of 0.85353 (99.35th percentile), this vulnerability exhibits substantial real-world exploitation activity.
KEV Information
CVSS Score
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HOpen in CalculatorAffected Products
| Vendor | Product | Version |
|---|---|---|
| microsoft | forefront threat management gateway | 2010 |
Multiple CVSS Assessments
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
References
- http://secunia.com/advisories/44857(Broken Link)
- http://www.securityfocus.com/bid/48181(Broken Link, Third Party Advisory, VDB Entry)
- http://www.securitytracker.com/id?1025637(Broken Link, Third Party Advisory, VDB Entry)
- https://docs.microsoft.com/en-us/security-updates/securitybulletins/2011/ms11-040(Patch, Vendor Advisory)
- https://exchange.xforce.ibmcloud.com/vulnerabilities/67736(Third Party Advisory, VDB Entry)
- https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A12642(Broken Link)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2011-1889(US Government Resource)
Weakness Type
CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer
CVE-2011-1889 is classified under CWE-119 — Improper Restriction of Operations within the Bounds of a Memory Buffer. Improper Restriction of Operations within the Bounds of a Memory Buffer occurs when software performs operations on a memory buffer but can read from or write to a memory location that is outside the intended boundary of the buffer. This is the parent category for many specific buffer error types including buffer overflows (CWE-120), buffer underflows, out-of-bounds reads (CWE-125), and out-of-bounds writes (CWE-787). These vulnerabilities occur when array indexes, pointer arithmetic, or size calculations allow access beyond allocated memory regions.
In the context of Microsoft Forefront Threat Management Gateway (TMG), this weakness class is particularly concerning because the product is widely deployed across enterprise and consumer environments. Memory buffer errors are consistently among the most exploited vulnerability classes. Out-of-bounds writes can overwrite adjacent memory including return addresses, function pointers, and security-critical data. Out-of-bounds reads can leak sensitive information including cryptographic keys and memory layout (defeating ASLR). Modern mitigations (ASLR, DEP, stack canaries) have made exploitation harder but not impossible. Browser exploits, kernel vulnerabilities, and firmware attacks frequently exploit buffer errors. Organizations using affected versions should understand that this weakness class frequently enables reliable exploitation paths that threat actors actively leverage in both targeted and opportunistic attacks.
Impact Analysis
CVE-2011-1889 carries a CVSS 3.1 score of 9.8 (CRITICAL) with the following impact characteristics.
Confidentiality (HIGH): An attacker who successfully exploits this vulnerability gains access to all data accessible by the affected component. In the context of Microsoft Forefront Threat Management Gateway (TMG), this can include sensitive configuration data, user credentials, proprietary business information, and any data the application processes or stores.
Integrity (HIGH): Successful exploitation enables an attacker to modify, corrupt, or destroy data within the affected system. This includes the potential to tamper with system files, install backdoors or persistent malware, alter critical configurations, and manipulate application logic to serve malicious purposes.
Availability (HIGH): The vulnerability can be exploited to cause complete denial of service, rendering the affected system or application unavailable to legitimate users. System crashes, infinite loops, or resource exhaustion may persist until manual administrative intervention restores normal operation.
Scope (Unchanged): The exploitation impact is contained within the security scope of the vulnerable component itself. While the damage within that scope can be severe with full compromise of the affected application, lateral impact on other systems requires additional exploitation steps.
With an EPSS score of 0.85353 (99.35th percentile), this vulnerability ranks among the most likely to be exploited in the wild, placing it well above the vast majority of all cataloged vulnerabilities in terms of real-world exploitation activity.
Exploit Maturity
CVE-2011-1889 demonstrates significant exploit maturity with confirmed active exploitation in the wild.
Active exploitation: This vulnerability is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming that it has been observed being actively exploited by threat actors. The KEV designation mandates federal agencies to apply remediation within a defined timeframe and serves as a strong signal of real-world risk.
Ransomware association: As of the current KEV catalog data, no direct ransomware association has been confirmed for CVE-2011-1889. However, the vulnerability's characteristics and confirmed exploitation in the wild mean it remains a viable vector for various threat actors including cybercriminals and advanced persistent threat groups.
Exploit availability: While specific public exploit code references were not identified in the NVD data, the vulnerability's inclusion in the KEV catalog confirms real-world exploitation. Threat intelligence sources and underground forums may host exploit tools not captured in public databases.
KEV remediation deadline: CISA set a remediation deadline of 2022-03-24 for federal agencies, underscoring the urgency of patching. Organizations beyond the federal sector should treat this deadline as a strong indicator of the risk level and prioritize remediation accordingly.
Remediation
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Apply vendor-provided security patches immediately. Apply updates per vendor instructions. Consult the official security advisory for specific patch versions and deployment guidance.
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Verify affected product versions in your environment. Affected products include: Forefront Threat Management Gateway (2010). Conduct an inventory of all instances across your organization to ensure comprehensive patch coverage and prevent any unpatched systems from remaining exposed.
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Implement interim mitigations if immediate patching is not feasible. Restrict network access to the affected service using firewall rules and access control lists. Limit exposure to trusted networks only and monitor for suspicious network traffic patterns targeting the vulnerable service.
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Enable enhanced monitoring and detection. Configure intrusion detection systems and endpoint detection and response (EDR) tools to detect exploitation attempts targeting CVE-2011-1889. Review security logs for indicators of compromise and establish alerting for anomalous behavior on systems running affected software.
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Conduct a post-patch vulnerability assessment. After applying patches, verify that the remediation was effective by running vulnerability scans against all previously affected systems. Confirm the vulnerability is no longer present and ensure no instances were missed during deployment.
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Review and update incident response procedures. Ensure your incident response plan accounts for potential exploitation of CVE-2011-1889. Document patching status and maintain evidence of remediation for compliance and audit purposes.
Technical Details
CVE-2011-1889 is a critical-severity vulnerability affecting Microsoft Forefront Threat Management Gateway (TMG). A remote code execution vulnerability exists in the Forefront Threat Management Gateway (TMG) Firewall Client Winsock provider that could allow code execution in the security context of the client application.
Attack Vector: The attack vector is NETWORK, meaning the vulnerability can be exploited remotely over the network without requiring the attacker to have local access to the target system. This significantly expands the potential attacker population and makes the vulnerability accessible to remote threat actors.
Attack Complexity: The attack complexity is LOW. Exploitation does not require specialized conditions, race conditions, or extensive preparation — making it accessible to a broad range of attackers including those with limited technical sophistication.
Underlying mechanism: The vulnerability stems from improper restriction of operations within the bounds of a memory buffer, where improper restriction of operations within the bounds of a memory buffer occurs when software performs operations on a memory buffer but can read from or write to a memory location that is outside the intended boundary of the buffer. In the context of Forefront Threat Management Gateway (TMG), this manifests when processing specially crafted input that triggers the underlying memory corruption or logic flaw, allowing the attacker to achieve code execution or other malicious outcomes.
Affected products: Forefront Threat Management Gateway (2010). Organizations should cross-reference their deployed versions against this list to assess their exposure to this vulnerability.
Frequently Asked Questions
What is CVE-2011-1889?
CVE-2011-1889 is a critical-severity vulnerability (CVSS 9.8) affecting Microsoft Forefront Threat Management Gateway (TMG). A remote code execution vulnerability exists in the Forefront Threat Management Gateway (TMG) Firewall Client Winsock provider that could allow code execution in the security context of the client application. It is listed in CISA's Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild.
Which products are affected by CVE-2011-1889?
The vulnerability affects Microsoft products including Forefront Threat Management Gateway. Affected versions include 2010. Organizations should consult the vendor's security advisory for the complete list of affected versions and available patches.
How do I fix CVE-2011-1889?
Apply updates per vendor instructions. Refer to the official vendor security advisory for specific patch downloads and deployment instructions. If immediate patching is not possible, implement interim mitigations such as restricting access to the vulnerable component, enabling enhanced monitoring, and educating users about potential attack vectors. Verify remediation effectiveness with post-patch vulnerability scanning.
How severe is CVE-2011-1889?
CVE-2011-1889 is rated CRITICAL with a CVSS 3.1 score of 9.8. Its EPSS score of 0.85353 places it in the 99.35th percentile for exploitation likelihood, meaning it is more likely to be exploited than 99.4% of all known vulnerabilities. The KEV remediation deadline was 2022-03-24, and the vulnerability's confirmed active exploitation makes it a high-priority remediation target. Organizations should treat patching as urgent regardless of whether they believe they are currently targeted.
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