CVE-2013-3918: Microsoft Windows Out-of-Bounds Write Vulnerability

CVE-2013-3918 is an out-of-bounds write vulnerability in Microsoft Windows that affects the InformationCardSigninHelper Class ActiveX control in icardie.dll. An attacker can trigger it by luring a user to view a specially crafted webpage, which may allow remote code execution with the same rights as the logged-on user. This matters because successful exploitation can give an attacker control over the affected system under the user's privileges, and the product may already be end-of-life or end-of-service, increasing long-term risk if it remains in use.

Defenders should treat this as a browser-reachable ActiveX issue on Windows endpoints and confirm all version, patch, and configuration details against the vendor advisory before acting.

How it works

The flaw is an out-of-bounds write inside the InformationCardSigninHelper Class ActiveX control (icardie.dll). When a user visits a malicious webpage that instantiates or interacts with this control, the control can write data outside the intended memory bounds. That memory corruption can be leveraged for remote code execution in the context of the current user.

No further exploit mechanics, specific memory layouts, or payload details are provided in the available facts. Attackers typically rely on social engineering or compromised sites to deliver the crafted page; once the control processes the malicious input, code runs with the privileges of the user who opened the page. Confirm exact exploitation conditions and any required user interaction against the vendor advisory.

Am I affected? How to find it in your systems

The vulnerability affects Microsoft Windows systems that expose the InformationCardSigninHelper Class ActiveX control via icardie.dll. This control is typically present on Windows clients that support older ActiveX-based identity or information-card features and can be reached through Internet Explorer or other browsers that still allow ActiveX.

• Inventory Windows endpoints (workstations, servers with desktop components, virtual desktops) and check for the presence of icardie.dll, commonly under system directories.
• Identify systems still configured to allow ActiveX controls, especially those running legacy browsers or with reduced security zones that permit ActiveX instantiation.
• Review software inventories and configuration management databases for any remaining use of Information Card or related ActiveX features; the product may be end-of-life or end-of-service.
• Look for telemetry signs of exploitation such as unexpected process creation or crashes originating from browser processes loading icardie.dll, anomalous ActiveX instantiations, or network connections following visits to untrusted sites. Specific indicators of compromise are not detailed in the facts and must be confirmed against vendor or threat-intelligence sources.

Because exact affected builds are not listed here, treat any Windows system still loading this control as potentially vulnerable until verified against the vendor advisory.

How to remediate

Apply the vendor-supplied update or mitigation instructions for CVE-2013-3918 as the primary remediation. Follow Microsoft guidance exactly; if the product is end-of-life or end-of-service and no mitigations are available, discontinue use of the affected component or the product itself, consistent with CISA direction.

• Deploy the security update through your normal patch-management process to all Windows systems that contain icardie.dll or the InformationCardSigninHelper control.
• After patching, verify that the control is no longer vulnerable (for example by confirming file versions or registry state as described in the advisory).
• Harden remaining ActiveX usage: disable the InformationCardSigninHelper Class or set the kill bit for the control if the advisory permits, and restrict ActiveX in Internet and Restricted Sites zones.
• For cloud or hosted Windows instances, also follow any applicable BOD 22-01 guidance.

Re-image or rebuild systems that cannot be patched if they are no longer supported.

If you can't patch immediately

Until the vendor update can be applied or the product can be retired, reduce exposure with compensating controls focused on the ActiveX attack surface.

• Segment affected endpoints so they cannot reach untrusted web content; place high-risk users behind stricter egress filtering or web proxies that block ActiveX-related content types.
• Disable or kill-bit the InformationCardSigninHelper ActiveX control via Group Policy or registry if operationally feasible, and enforce browser settings that prevent ActiveX instantiation from the Internet zone.
• Apply virtual patching or WAF/IPS rules that detect and block known exploit patterns for this class of ActiveX memory-corruption issues; confirm signatures against current vendor or security-vendor guidance.
• Increase monitoring of browser processes loading icardie.dll, unexpected child processes, and anomalous outbound connections after web browsing. Alert on crashes or memory-corruption events involving the control.
• Limit user privileges so that even successful code execution yields only standard-user rights, and enforce application allow-listing where possible.

These measures lower risk but do not eliminate it; plan for full remediation or product discontinuation.

If your data may have been exposed

Actively exploited vulnerabilities of this type can lead to system compromise and subsequent data breaches. If you suspect exploitation, isolate the host, preserve forensic evidence, and investigate for lateral movement or data access under the compromised user context. Known ransomware use of this CVE is not documented in the available facts.

You can run a free exposure scan of your email address against known breach data sets to determine whether credentials or personal information associated with your accounts have already appeared in public breach collections.