CVE-2012-4792
Microsoft Internet Explorer Use-After-Free Vulnerability
Description
CVE-2012-4792 is a high-severity use-after-free vulnerability in Microsoft Internet Explorer versions 6 through 8 that allows remote attackers to execute arbitrary code via a crafted website. The vulnerability triggers access to a CDwnBindInfo object that was either not properly allocated or has already been deleted, enabling memory corruption and code execution. With a CVSS v3.1 base score of 8.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H), this vulnerability was exploited in the wild in December 2012 as part of a sophisticated watering hole attack against the Council on Foreign Relations website. It is listed in CISA's KEV catalog and carries an EPSS score of 0.9183 (99.7th percentile).
KEV Information
CVSS Score
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HOpen in CalculatorAffected Products
| Vendor | Product | Version |
|---|---|---|
| microsoft | internet explorer | 6; 7; 8 |
Multiple CVSS Assessments
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
References
- http://blog.fireeye.com/research/2012/12/council-foreign-relations-water-hole-attack-details.html(Broken Link)
- http://blogs.technet.com/b/srd/archive/2012/12/29/new-vulnerability-affecting-internet-explorer-8-users.aspx(Broken Link)
- http://blogs.technet.com/b/srd/archive/2012/12/31/microsoft-quot-fix-it-quot-available-for-internet-explorer-6-7-and-8.aspx(Broken Link)
- http://eromang.zataz.com/2012/12/29/attack-and-ie-0day-informations-used-against-council-on-foreign-relations/(Third Party Advisory)
- http://labs.alienvault.com/labs/index.php/2012/just-another-water-hole-campaign-using-an-internet-explorer-0day/(Broken Link)
- http://packetstormsecurity.com/files/119168/Microsoft-Internet-Explorer-CDwnBindInfo-Object-Use-After-Free.html(Third Party Advisory, VDB Entry)
- http://technet.microsoft.com/security/advisory/2794220(Patch, Vendor Advisory)
- http://www.kb.cert.org/vuls/id/154201(Third Party Advisory, US Government Resource)
- http://www.us-cert.gov/cas/techalerts/TA13-008A.html(Third Party Advisory, US Government Resource)
- http://www.us-cert.gov/cas/techalerts/TA13-015A.html(Third Party Advisory, US Government Resource)
- https://docs.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-008(Patch, Vendor Advisory)
- https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/windows/browser/ie_cbutton_uaf.rb(Third Party Advisory)
- https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A16361(Broken Link)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2012-4792(US Government Resource)
Weakness Type
Use-After-Free Memory Corruption
CVE-2012-4792 is a use-after-free vulnerability, a class of memory corruption flaw where a program continues to reference a memory location after it has been freed. In Internet Explorer's rendering engine, a CDwnBindInfo object is freed during certain DOM operations, but a dangling pointer to the freed memory remains. When the browser subsequently accesses this pointer, it reads from memory that may have been reallocated for a different purpose. An attacker can manipulate the heap layout to place controlled data in the freed memory region, causing the browser to execute attacker-supplied code when it dereferences the stale pointer. Use-after-free vulnerabilities are among the most dangerous classes of software flaws because they enable reliable code execution through heap manipulation techniques.
Impact Analysis
Remote Code Execution via Browser is the direct consequence of CVE-2012-4792. A user merely needs to visit a malicious or compromised website to trigger the vulnerability, resulting in arbitrary code execution with the privileges of the browser process.
Confidentiality Impact is maximum (C:H). Successful exploitation grants the attacker code execution in the context of the user's browser session, providing access to all data accessible to that user, including browser cookies, saved passwords, local files, and potentially corporate network resources if the user is connected to a corporate environment.
Integrity Impact is maximum (I:H). Code execution allows the attacker to install malware, create backdoor accounts, modify system files, and establish persistent access to the compromised system. The attacker can deploy rootkits, keyloggers, or remote access trojans that survive browser closure and system reboots.
Availability Impact is maximum (A:H). The attacker can render the system inoperable, encrypt files for ransom, or use the compromised machine as a pivot point for further network attacks. The initial browser crash from the use-after-free can also cause immediate availability loss.
Historical Exploitation Context: This vulnerability was exploited as a zero-day in December 2012 through a watering hole attack targeting the Council on Foreign Relations (CFR) website. Visitors to the CFR website using vulnerable versions of Internet Explorer were silently compromised. The EPSS score of 0.9183 (99.7th percentile) reflects the extensive exploitation history. CISA lists the ransomware association as "Unknown," but the vulnerability has been incorporated into exploit kits and the Metasploit framework.
Exploit Maturity
CVE-2012-4792 was exploited as a zero-day vulnerability in December 2012 and has since been incorporated into multiple exploit frameworks. It is listed in CISA's KEV catalog with a remediation deadline of August 13, 2024. The EPSS score of 0.9183 (99.7th percentile) confirms its extensive exploitation history.
Zero-Day Watering Hole Attack: The vulnerability was first discovered in a sophisticated watering hole attack targeting the Council on Foreign Relations (CFR) website in December 2012. Attackers compromised the CFR website and embedded exploit code that silently targeted visitors using Internet Explorer 6, 7, or 8. This was a targeted espionage operation aimed at foreign policy professionals and government officials.
Metasploit Integration: The exploit has been integrated into the Metasploit framework as the ie_cbutton_uaf module, making it readily available for penetration testing and, unfortunately, for less sophisticated attackers. Public availability in Metasploit significantly lowered the barrier to exploitation.
Exploit Kit Adoption: Following public disclosure and Metasploit integration, the exploit was adopted by multiple commercial exploit kits used in drive-by download campaigns, broadening its impact from targeted espionage to mass exploitation.
Ransomware Association: CISA lists the ransomware status as "Unknown." While the original exploitation was espionage-focused, the subsequent availability in exploit kits means the vulnerability has likely been used across a wide spectrum of attack objectives including ransomware delivery.
Remediation
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Apply Microsoft security update MS13-008 which addresses CVE-2012-4792. The security bulletin MS13-008 provides cumulative security updates for Internet Explorer that resolve this vulnerability. Apply the update through Windows Update or download it directly from the Microsoft Security Bulletin.
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Upgrade from Internet Explorer 6, 7, and 8 to a modern, supported web browser. These Internet Explorer versions have reached end of life and no longer receive security updates. Migrate to Microsoft Edge, Google Chrome, Mozilla Firefox, or another actively maintained browser that benefits from modern exploit mitigations such as ASLR, DEP, and sandboxing.
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Upgrade the underlying Windows operating system if it still supports only legacy Internet Explorer versions. Systems running Windows XP, Vista, or early Windows 7 configurations should be upgraded to a supported operating system version that provides modern security protections including Control Flow Guard, Credential Guard, and Virtualization-Based Security.
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Implement network-level protections including web content filtering, intrusion prevention systems, and DNS-based security to block access to known malicious websites that serve browser exploits. Deploy endpoint detection and response (EDR) solutions that can detect and block exploit attempts in real time.
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Apply the Microsoft Fix it workaround (referenced in the original Microsoft advisory at http://technet.microsoft.com/security/advisory/2794220) as an interim measure if the full security update cannot be applied immediately. This temporary workaround modifies browser behavior to prevent the use-after-free from being triggered, though it should not be considered a permanent solution.
Technical Details
CVE-2012-4792 is a use-after-free vulnerability in Microsoft Internet Explorer versions 6 through 8 that enables remote code execution through crafted web content.
CVSS Vector Breakdown: The vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H produces a base score of 8.8. The network attack vector (AV:N) means exploitation occurs through web browsing. Low attack complexity (AC:L) indicates no special conditions beyond user interaction. No privileges are required (PR:N), but user interaction is required (UI:R) since the victim must visit a malicious website. The scope is unchanged (S:U), and all impact metrics are high (C:H/I:H/A:H), reflecting full system compromise through browser exploitation.
Vulnerability Mechanism: The vulnerability exists in Internet Explorer's handling of CDwnBindInfo objects, which are used during the binding and downloading of resources referenced in web pages. During certain DOM manipulation sequences, a CDwnBindInfo object is freed while a reference to it still exists in the browser's internal data structures. When the browser subsequently accesses this stale reference, it dereferences a pointer to freed memory.
Exploitation Technique: The attacker crafts a web page that triggers the specific sequence of DOM operations that causes the CDwnBindInfo object to be freed prematurely. Through heap spraying and heap manipulation techniques, the attacker arranges for the freed memory to be reallocated with attacker-controlled data. When Internet Explorer dereferences the stale pointer, it reads the attacker's data as a vtable pointer, redirecting code execution to attacker-supplied shellcode. The use of heap spray techniques ensures reliable exploitation by filling large portions of memory with the attack payload.
Historical Significance: This vulnerability is emblematic of the use-after-free vulnerability class that plagued Internet Explorer throughout its lifecycle. The CDwnBindInfo use-after-free was one of many similar vulnerabilities discovered in IE's complex DOM implementation, highlighting the challenges of memory safety in C++ codebases handling complex document object models.
Frequently Asked Questions
What is CVE-2012-4792?
CVE-2012-4792 is a use-after-free vulnerability in Microsoft Internet Explorer 6 through 8 that allows remote attackers to execute arbitrary code when a user visits a specially crafted website. It was first exploited as a zero-day in December 2012 during a watering hole attack against the Council on Foreign Relations website.
Is CVE-2012-4792 still relevant today?
While Internet Explorer 6-8 are long obsolete, CISA maintains this CVE in its KEV catalog because some legacy systems and embedded applications still use these browsers. Organizations should ensure no systems in their environment still run these vulnerable IE versions. The vulnerability also serves as a case study for understanding use-after-free exploitation techniques.
How was CVE-2012-4792 used in the Council on Foreign Relations attack?
Attackers compromised the CFR website and embedded malicious code that exploited CVE-2012-4792 in visitors' browsers. This "watering hole" technique targeted foreign policy professionals and government officials who regularly visited the site. Visitors using Internet Explorer 6, 7, or 8 were silently exploited, with malware installed on their systems without any visible indication.
Is there a public exploit available for CVE-2012-4792?
Yes. The vulnerability has been integrated into the Metasploit framework as the ie_cbutton_uaf exploit module, and multiple proof-of-concept exploits have been published. This public availability means any system still running IE 6-8 is at extreme risk and should be upgraded or isolated immediately.
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