CVE-2013-5065: Microsoft Windows Kernel Privilege Escalation Vulnerability

CVE-2013-5065 is a privilege-escalation vulnerability in the Microsoft Windows kernel component NDProxy.sys. Improper input validation can let a local attacker raise their privileges on the system. For IT and security teams this matters because a foothold with limited rights can be turned into full administrative control, increasing the impact of any initial compromise.

Public detail is limited to the component and weakness class described by CISA; confirm exact affected builds, patch identifiers, and configuration notes against the vendor advisory before acting.

How it works

The flaw is classified as CWE-20 (Improper Input Validation). NDProxy.sys runs in the kernel and processes input that is not adequately checked. A local attacker who can already execute code on the machine can supply malformed input that the driver mishandles. Because the component operates with kernel privileges, successful abuse can allow the attacker to run code at a higher integrity level than their original account.

No remote unauthenticated path is described in the provided facts; exploitation requires local access. Exact trigger conditions, IOCTL details, or exploit mechanics are not supplied here and must be taken only from the vendor advisory or trusted analysis that cites it. Do not assume specific payloads or reliability without that confirmation.

Am I affected? How to find it in your systems

The vulnerability affects Microsoft Windows systems that include the NDProxy.sys kernel driver. This driver is typically present on Windows hosts that use certain networking or modem-related proxy functionality, but presence and exposure depend on the installed OS edition and configuration.

• Inventory Windows endpoints and servers with your asset-management or CMDB tools; flag any host still running older Windows builds that have not received the corresponding security update.
• Confirm the presence of NDProxy.sys (commonly under the system drivers directory) and note its file version; compare against the fixed versions listed in the Microsoft advisory.
• Review local accounts and service accounts that have interactive or service logon rights; any low-privilege local user is a potential starting point for escalation.
• Check endpoint-detection, Sysmon, or kernel-audit logs for unusual interactions with NDProxy.sys, unexpected privilege changes, or crashes in the driver around the time of suspicious local activity. Absence of such telemetry does not prove safety; it only means you lack visibility.

Because version ranges and superseding bulletins are not listed in the facts above, treat every unpatched Windows system as potentially in scope until you verify against the vendor advisory.

How to remediate

Patch first. Apply the security updates Microsoft released for this vulnerability, following the vendor’s instructions exactly. CISA’s required action is to apply updates per vendor instructions; that remains the primary fix.

• Use your standard patch-management pipeline (WSUS, ConfigMgr, Intune, or equivalent) to deploy the relevant update and verify installation success via update history or compliance reports.
• After patching, reboot if the advisory requires it so the updated kernel driver is loaded.
• Re-inventory driver versions to confirm NDProxy.sys matches the fixed build.
• For defense-in-depth against the broader class of local privilege-escalation bugs: enforce least privilege, remove unnecessary local admin rights, enable Credential Guard and other kernel protections where supported, and keep attack-surface reduction rules enabled.

Do not rely on workarounds alone once a vendor patch is available.

If you can't patch immediately

If immediate patching is blocked by change windows or compatibility constraints, reduce risk with compensating controls while you schedule the update.

• Segment hosts that cannot be patched; limit lateral movement paths so a local compromise stays contained.
• Restrict who can log on locally or via RDP/console to only essential administrators; prefer just-in-time privileged access.
• If the advisory or your testing shows a way to disable or unload the affected functionality without breaking critical services, consider that temporary measure—but only after validating business impact.
• Apply virtual patching or host-based controls that can block known exploitation patterns for this driver class, if your EDR or WAF-like host agent supports them; tune to avoid false positives.
• Increase monitoring: alert on privilege-escalation indicators, unexpected kernel-module loads, and anomalous process token modifications. Retain logs long enough for investigation.

These steps lower likelihood and impact but do not replace the vendor update. Known ransomware use is not documented for this CVE in the provided facts; still treat local privilege escalation as a high-priority risk.

If your data may have been exposed

Actively exploited privilege-escalation vulnerabilities frequently appear in breach chains once an attacker has initial access. If you have evidence of exploitation or cannot rule it out, follow your incident-response process: isolate affected hosts, preserve memory and disk evidence, rotate credentials that may have been accessible from the elevated context, and assess what data the attacker could have reached. You can also run a free exposure scan of your email addresses against known breach data sets to see whether associated accounts appear in prior leaks, then force password resets and enable phishing-resistant MFA where needed.