CVE-2010-0806 — Microsoft Internet Explorer | CVSS 9.3 HIGH

HIGH

CVSS 9.3 HIGH  ·  EPSS 89%  ·  Microsoft Internet Explorer

Severity Overview

Summary

Use-after-free vulnerability in the Peer Objects component (aka iepeers.dll) in Microsoft Internet Explorer 6, 6 SP1, and 7 allows remote attackers to execute arbitrary code via vectors involving access to an invalid pointer after the deletion of an object, as exploited in the wild in March 2010, aka "Uninitialized Memory Corruption Vulnerability."

Analyst Takeaway

The attack is launched over the network (remotely exploitable without physical access). This vulnerability is already in CISA KEV, which means exploitation has been confirmed in the wild — treat this as active risk, not theoretical exposure. The CVSS score places this in critical territory, so internet-facing systems and high-value assets should be prioritized for immediate remediation or compensating controls. Microsoft Internet Explorer is associated with technology that is commonly deployed in enterprise environments, so defenders should assume a higher probability of broad target interest and prioritize validation across the environment. The ATT&CK mapping suggests public-facing exploitation risk, so external exposure validation should be part of immediate triage. In parallel with patching, defenders should review external exposure, hunt for signs of exploitation, and validate whether compensating controls are in place for vulnerable assets.

MITRE ATT&CK Mapping

• T1203 – Exploitation for Client Execution
  Rationale: The vulnerability appears tied to a client application such as a browser, document handler, or end-user productivity software.
• T1190 – Exploit Public-Facing Application
  Rationale: The product appears likely to be internet-facing or commonly exposed in enterprise environments.

Detection Guidance

• T1203 — Exploitation for Client Execution
  • Inspect endpoint telemetry for suspicious execution chains: scripting engines or download utilities launched as children of browsers, Office applications, PDF readers, or other client-side software.
  • Look for LOLBin usage (certutil, mshta, rundll32, regsvr32, wmic) with suspicious arguments spawned from document-handling parent processes.
  • Review email attachment and file download activity correlated with any suspicious process execution on the same endpoint within the same time window.
• T1190 — Exploit Public-Facing Application
  • Inspect web server, reverse proxy, load balancer, and WAF logs for abnormal request patterns — unusual URIs, oversized payloads, HTTP verb abuse, or encoding anomalies.
  • Monitor for spikes in HTTP 4xx/5xx responses that may indicate probing or failed exploitation attempts preceding a successful hit.
  • Review outbound connections from affected servers for unexpected command-and-control callbacks or secondary payload retrieval to external IPs.
  • Validate which internet-facing assets are running the vulnerable version and verify whether compensating controls (WAF rules, network ACLs) are in place and effective.

Hunting Considerations

These are proactive hunts mapped to the ATT&CK techniques identified for this CVE. Run them now — do not wait for an alert to fire.

• T1203 — Exploitation for Client Execution
  • Parent-child process chains: Search for scripting engines (PowerShell, cmd.exe, wscript.exe, cscript.exe, mshta.exe) or download utilities (certutil, bitsadmin, curl) spawned as direct children of Office applications, browsers, or PDF readers. These chains are rarely legitimate.
  • LOLBin execution: Hunt for Living-off-the-Land Binaries — regsvr32, rundll32, mshta, certutil, wmic, odbcconf — executing from unusual working directories or with command lines containing encoded strings, remote paths, or -enc / -nop / IEX patterns.
  • Network connections from client apps: Flag outbound connections to new external IPs from browser, Office, or document-handling processes that do not match known CDN or update infrastructure. These indicate the exploited process reaching out for a secondary payload.
  • Windows Event IDs: Event 4688 (process creation with full command line) and Sysmon Event 1 are your primary sources. Filter for suspicious parent-child pairs. Sysmon Event 3 (network connection) from document handlers is a high-fidelity indicator.
  • Correlation with delivery: Check email gateway and proxy logs for attachment opens or file downloads on the same host in the 30 minutes before any suspicious process execution — this helps confirm the initial delivery vector.
• T1190 — Exploit Public-Facing Application
  • Web/app server logs: Search for unusual HTTP methods, requests to non-standard paths, oversized payloads, or encoding anomalies (URL-encoded or double-encoded sequences) targeting the vulnerable application. Cluster by source IP and look for low-volume probing patterns before any successful hit.
  • Process telemetry: Hunt for child processes spawned by the web server or application process (e.g., apache2, nginx, w3wp.exe, java). Web server processes should not be launching shells, scripting engines (PowerShell, bash, python), or download utilities.
  • Outbound connections from the server: Alert on unexpected outbound HTTP/S or DNS from the application server to external IPs not in your CDN or update allowlist — this is a common secondary payload retrieval indicator post-exploitation.
  • File system writes: Look for new files written to web root directories, temp folders, or cron directories by the application process — especially scripts or executables placed there after an unusual inbound request.
  • Internal pivot follow-on: After gaining a foothold, attackers move laterally. Search for new internal connections originating from the compromised server in the hour following any suspicious external request.

Recommended Actions

Immediate (0–24 Hours)

• Inventory: Identify all systems running Microsoft Internet Explorer. Include production, staging, dev, and cloud environments — untracked instances are the most likely to remain unpatched.
• Validate internet-facing exposure: Determine which of the affected systems are reachable from the public internet. Prioritize these for immediate remediation or compensating controls.
• Apply compensating controls now: For systems that cannot be patched immediately, implement temporary mitigations: restrict access via firewall rules or ACLs, add WAF rules if applicable, disable or isolate the vulnerable component if feasible without breaking critical operations.

Remediation

• Apply the vendor patch: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
• CISA directive deadline: 2026-06-03 — this is the mandatory deadline for US federal civilian agencies under BOD 22-01. All organizations should treat this date as a strong target regardless of federal mandate.
• Verify remediation: After patching, confirm the correct version is installed on all affected hosts. Run a vulnerability scan or use your asset management tooling to verify — do not rely solely on change tickets.
• Post-patch review: After patching, review web server and application logs for signs of exploitation prior to remediation. A successful exploit may have left behind a web shell, new account, or scheduled task.

Detection Coverage

• Verify ATT&CK coverage: Confirm your SIEM and EDR have detection logic in place for T1203, T1190. Review the Detection Guidance and Hunting Considerations sections of this alert for the specific log sources and behavioral patterns to monitor.
• Threat intelligence feeds: Monitor your TI feeds and vendor advisory channels for published indicators of compromise (IOCs), proof-of-concept exploit releases, or active campaign reporting associated with this CVE — these should trigger an immediate hunt even if no internal alerts have fired.

Vulnerability Details

Additional Notes

https://learn.microsoft.com/en-us/security-updates/securityadvisories/2010/981374 ; https://nvd.nist.gov/vuln/detail/CVE-2010-0806