Microsoft Windows Out-of-Bounds Write Vulnerability (CVE-2013-3918)
Published In CISA KEV since Sources: pwn.watch, CVE.org
What is affected, what to do
The InformationCardSigninHelper Class ActiveX control in icardie.dll in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, and Windows RT Gold and 8.1 allows remote attackers to execute arbitrary code or cause a denial of service (out-of-bounds write) via a crafted web page that is accessed by Internet Explorer, as exploited in the wild in November 2013, aka "InformationCardSigninHelper Vulnerability."
The vulnerability is being actively exploited; treat it as a priority. The available sources name no fixed version. Check the vendor guidance in the references below. Immediate actions, mitigation and detection rules are in the runbook below.
- Affected
- Microsoft Windows Server 2008
eq r2..r2 - Microsoft Windows Server 2008
eq sp2..sp2 - Microsoft Windows Server 2012
eq r2..r2
- Microsoft Windows Server 2008
Not sure whether and how you are affected? Ask a question about this vulnerability
Metrics
8.8
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
8.8
CVSS v3
Severity High on the scale from 0 to 10.
Source: pwn.watch, CVE.org
73.7 %
EPSS score
High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
Source: FIRST EPSS, percentile 99.47
Show all metrics
- Severity
- Critical
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 223.15 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- actively exploited
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 8.8 Methodology
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 8.8
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 73.7 %
- High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 99.47
- Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- Actively exploited
- Published
In CISA KEV since
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- CISA assessment (SSVC)
- Exploitation: active · not automatable · Technical impact: total
- Source: CISA Vulnrichment, as of 4 October 2025
CWE
CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.
Read in glossary- CWE-787
Response and mitigation
Why act now?
Prioritisation rationale
This flaw is network-reachable without authentication and only needs a user to open a crafted page in Internet Explorer, typically through watering-hole sites or phishing links. Exploitation likelihood is very high, though CISA reports no known ransomware use. Its late KEV addition signals that old browser exploits are still being aimed at forgotten legacy hosts. For estates running current Windows without IE, the residual risk is low. Where EoL Windows still has web access — common in OT, medical and manufacturing environments within NIS2 scope — treat it as critical and close it within 24 hours through isolation or the kill bit.
Runbook step 1
Immediate response (0-24 h)
- Inventory legacy clients: Identify every host running Windows XP, Vista, 7, 8, 8.1, RT, Server 2003, 2008/2008 R2 or 2012/2012 R2 via CMDB, EDR or
Get-ADComputer -Filter * -Properties OperatingSystem. Pay particular attention to OT HMIs, lab equipment, kiosks and jump hosts where Internet Explorer is still usable. - Verify patch status: Microsoft fixed this flaw in a cumulative ActiveX kill-bit update. A patch is available from the vendor — look up the KB number in the vendor advisory. Use WSUS, SCCM/Intune or
Get-HotFixto find hosts missing it, and remediate wherever the OS still receives updates. - Set the kill bit where patching is impossible: Push
HKLM\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{19916E01-B44E-4E31-94A4-4696DF46157B}→Compatibility Flags(DWORD) =0x400via GPO. On 64-bit systems, set it underWow6432Nodeas well. Verify the CLSID against the Microsoft advisory before rollout. - Retire Internet Explorer: Disable IE via GPO or remove the Windows feature on all remaining hosts. Move users to a supported browser without ActiveX support.
- Cut EoL systems off from the web: Immediately block direct web access for unsupported Windows versions with a proxy deny rule or a firewall rule on the source subnets. CISA advises discontinuing use of the product.
- Inventory legacy clients: Identify every host running Windows XP, Vista, 7, 8, 8.1, RT, Server 2003, 2008/2008 R2 or 2012/2012 R2 via CMDB, EDR or
Runbook step 2
Mitigation layers
- Network segmentation: Move legacy Windows hosts into a dedicated VLAN with no outbound HTTP/HTTPS (TCP 80/443). Allow only explicitly approved destinations through a proxy allowlist. In critical-infrastructure environments, enforce IT/OT zone separation (IEC 62443).
- Web proxy / IPS: Block or alert on
MSIEuser agents originating from client networks. Enable vendor IPS signatures for the InformationCardSigninHelper flaw (search Suricata/ET rulesets forCVE-2013-3918or CLSID19916E01). Strip or block HTML containing<object classid="clsid:19916E01-…">at the proxy. - Endpoint hardening: Set ActiveX controls to "Disable" in the Internet and Intranet IE security zones via GPO. Enable Enhanced Protected Mode where IE is unavoidable. Use AppLocker or WDAC to restrict
iexplore.exeto named legacy applications. - Least privilege: Code runs with the logged-on user's rights. Remove local admin rights from standard users and use separate admin accounts with no internet access.
- Lifecycle governance: Record EoL replacement in the risk register (ISO 27001 A.8.8) with an owner and a deadline. Where replacement is impossible, document the compensating controls and obtain formal risk acceptance.
Runbook step 3
Detection rules
- Sysmon EID 7 (image load):
iexplore.exeloadingicardie.dllis rare in modern estates. Sigma shape:Image|endswith: '\iexplore.exe' AND ImageLoaded|endswith: '\icardie.dll'. - EDR process ancestry / Sysmon EID 1 / Security EID 4688: Suspicious children of
iexplore.exesuch ascmd.exe,powershell.exe,rundll32.exe,regsvr32.exe,mshta.exeorwscript.exe. KQL:DeviceProcessEvents | where InitiatingProcessFileName =~ "iexplore.exe" and FileName in~ ("cmd.exe","powershell.exe","rundll32.exe","mshta.exe","regsvr32.exe"). - Proxy/web logs: Responses containing HTML that references CLSID
19916E01-B44E-4E31-94A4-4696DF46157B. Also flagMSIEsessions to unknown or newly registered domains. SPL:index=proxy useragent="*MSIE*" | stats count by src, dest_host. - Memory-resident payloads: Historical exploitation included diskless payloads. Hunt for Sysmon EID 8 (CreateRemoteThread) and EID 10 (ProcessAccess) with
iexplore.exeas the source. Also look for unusual outbound connections fromiexplore.exeto non-standard ports (Sysmon EID 3, Zeekconn.log). - Crash artefacts: Application log EID 1000/1001 with faulting module
icardie.dllcan indicate failed exploitation attempts.
- Sysmon EID 7 (image load):
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
The InformationCardSigninHelper Class ActiveX control in icardie.dll in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, and Windows RT Gold and 8.1 allows remote attackers to execute arbitrary code or cause a denial of service (out-of-bounds write) via a crafted web page that is accessed by Internet Explorer, as exploited in the wild in November 2013, aka "InformationCardSigninHelper Vulnerability."
Source: pwn.watch, NVD (NIST), cvelistv5, CISA KEV Catalog, CVE.org (MITRE)
Vendors and products
- Microsoft Microsoft Windows 7
- Microsoft Microsoft Windows 8 Professional Edition
- Microsoft Microsoft Windows 8.1
- Microsoft Microsoft Windows RT Gold
- Microsoft Microsoft Windows RT 8.1
- Microsoft Microsoft Windows Server 2003
- Microsoft Microsoft Windows Server 2008
- Microsoft Microsoft Windows Server 2012
- Microsoft Microsoft Windows Vista Gold on X64
- Microsoft Microsoft Windows XP Service Pack 1 Home Edition
Affected operating systems
| Windows | microsoft | windows_7 | — |
| Windows | microsoft | windows_8 | — |
| Windows | microsoft | windows_8.1 | — |
| Windows | microsoft | windows_rt | — |
| Windows | microsoft | windows_rt_8.1 | — |
| Windows | microsoft | windows_server_2003 | — |
| Windows | microsoft | windows_server_2008 | r2 |
| Windows | microsoft | windows_server_2008 | sp2 |
| Windows | microsoft | windows_server_2012 | r2 |
| Windows | microsoft | windows_server_2012 | — |
| Windows | microsoft | windows_vista | — |
| Windows | microsoft | windows_xp | — |
Weakness classes (CWE)
CWE-787Out-of-bounds Write
Base
The product writes data past the end, or before the beginning, of the intended buffer.
Entry at MITRE CWE-787
Public exploit references
Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.
| CISA KEV Catalog | CISA Known Exploited Vulnerability (opens in a new tab)cisa.gov | actively exploited |
References & sources
- us-cert.govTA13-317AThird-party advisory, x_refsource_CERT, Third-party advisory, US government resource
- darkreading.comvulnerability/new-ie-vulnerability-found-in-the-wild-s/240163814x_refsource_MISC, Broken link
- docs.microsoft.comMS13-090Vendor advisory, x_refsource_MS, Patch, Vendor advisory, pwn-watch
- fireeye.comblog/technical/2013/11/new-ie-zero-day-found-in-watering-hole-a…x_refsource_MISC, Third-party advisory
- oval.cisecurity.orgoval:org.mitre.oval:def:19089Vulnerability database, signature, x_refsource_OVAL, Broken link, Third-party advisory
- isc.sans.eduforums/diary/16985x_refsource_MISC, Third-party advisory
- blogs.technet.comb/msrc/archive/2013/11/11/activex-control-issue-being-addressed…x_refsource_CONFIRM, Third-party advisory
- microsoft.comen-us/msrc/blog/2013/11/technical-details-of-the-targeted-attac…Vendor advisory, Vendor advisory
- cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2013-3918government-resource, US government resource
- pwn.watchpwn.watch: Microsoft Windows: 3 exploited vulnerabilities (CVE-2011-3402, CVE-2013-3918, CVE-2021-43226)pwn-watch
- docs.microsoft.comMicrosoft advisory: Microsoft Windowspwn-watch
- Microsoft Security Update GuideMicrosoft advisory: Microsoft Windowspwn-watch
- NVD (NIST)NVD: CVE-2011-3402pwn-watch
- NVD (NIST)NVD: CVE-2013-3918pwn-watch
- NVD (NIST)NVD: CVE-2021-43226pwn-watch
- cisa.govCISA Known Exploited Vulnerabilities Catalogpwn-watch
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<a href="https://intel.neosec.eu/en/cve/CVE-2013-3918"><img src="https://intel.neosec.eu/badge/cve/CVE-2013-3918.svg?lang=en" alt="CVE-2013-3918 – NEOSEC Intel" height="20"></a>