1. Introduction
The Microsoft IE FRAME/IFRAME/EMBED Tag Overflow vulnerability, also known as the Bofra worm detection, is a critical flaw affecting Internet Explorer. This allows a malicious website to execute code on a user’s computer without their knowledge. Systems running vulnerable versions of Internet Explorer are at risk of complete compromise. This can lead to loss of data confidentiality, integrity and availability.
2. Technical Explanation
The vulnerability stems from how Internet Explorer handles malformed IFRAME tags within web pages. An attacker crafts a webpage containing an exploit that overflows a buffer when processing these tags. This allows them to execute arbitrary code on the affected system. The CVE associated with this issue is CVE-2004-1050. A typical attack involves tricking a user into visiting a website hosting the malicious page.
- Root cause: Insufficient bounds checking when parsing IFRAME tags in Internet Explorer.
- Exploit mechanism: An attacker creates an HTML file with a specially crafted IFRAME tag that overflows a buffer, allowing for arbitrary code execution. For example, embedding a malicious script within the IFRAME source attribute.
- Scope: Affected platforms are those running vulnerable versions of Microsoft Internet Explorer.
3. Detection and Assessment
Confirming infection requires checking for signs of the worm or its associated files. A quick check involves verifying the version of Internet Explorer installed. Thorough assessment includes scanning with an anti-malware solution.
- Quick checks: Check the Internet Explorer version in Help > About Internet Explorer.
- Scanning: Nessus vulnerability ID 15ea74a4 can detect this issue. This is provided as an example only.
- Logs and evidence: Look for unusual network activity or unexpected files in temporary directories (e.g., %TEMP%).
reg query "HKLMSOFTWAREMicrosoftInternet ExplorerVersion"4. Solution / Remediation Steps
Fixing this issue requires verifying compromise and reinstalling the operating system if necessary. Follow these steps carefully to ensure a complete removal of the worm.
4.1 Preparation
- Stop any unnecessary services that might interfere with re-installation. A roll back plan involves restoring from backup or snapshot if issues occur.
- A change window may be required, and approval should be sought from the IT security team.
4.2 Implementation
- Step 1: Disconnect the affected system from the network to prevent further spread.
- Step 2: Run a full scan with an up-to-date anti-malware solution.
- Step 3: If malware is detected and removed, apply all available Windows updates.
- Step 4: If the system remains compromised, re-install the operating system from trusted media.
4.3 Config or Code Example
Before
After
4.4 Security Practices Relevant to This Vulnerability
Several practices can help prevent this type of issue. Least privilege reduces the impact if exploited. Input validation blocks unsafe data. A regular patch cadence ensures systems are up-to-date with the latest security fixes.
- Practice 1: Implement least privilege to limit the damage caused by successful exploitation.
- Practice 2: Enforce input validation on web applications to prevent malicious code from being injected.
4.5 Automation (Optional)
5. Verification / Validation
Confirming the fix involves verifying that Internet Explorer is updated and no longer vulnerable. Re-run earlier detection methods to confirm removal of the worm. A simple service smoke test includes browsing trusted websites.
- Post-fix check: Check the Internet Explorer version in Help > About Internet Explorer; ensure it’s a patched version.
- Re-test: Re-run the Nessus scan (ID 15ea74a4) to confirm the vulnerability is no longer detected.
- Smoke test: Browse to a trusted website like bbc.co.uk to verify normal functionality.
- Monitoring: Monitor system logs for unusual network activity or unexpected file creations.
reg query "HKLMSOFTWAREMicrosoftInternet ExplorerVersion"6. Preventive Measures and Monitoring
Update security baselines to include the latest patches. Add checks in CI/CD pipelines to prevent vulnerable software from being deployed. Implement a sensible patch or config review cycle that fits the risk profile of the organisation.
- Baselines: Update your Windows baseline configuration to ensure all critical security updates are applied automatically.
- Pipelines: Integrate vulnerability scanning into your CI/CD pipeline to identify and block vulnerable software components.
- Asset and patch process: Review and apply security patches at least monthly, or more frequently for critical vulnerabilities.
7. Risks, Side Effects, and Roll Back
Re-installing the operating system can result in data loss if backups are not performed. Service downtime is expected during the re-installation process. Roll back involves restoring from backup or snapshot.
- Risk or side effect 2: Service downtime during OS re-installation; plan for scheduled maintenance window.
- Roll back: 1) Restore from the pre-re-installation system snapshot. 2) If no snapshot, restore data from the latest backup.
8. References and Resources
- Vendor advisory or bulletin: https://www.microsoft.com/en-us/security/vulnerability/MS04-017
- NVD or CVE entry: https://nvd.nist.gov/vuln/detail/CVE-2004-1050
- Product or platform documentation relevant to the fix: https://learn.microsoft.com/en-us/windows/security/threats/malware/bofra