Urgent Patch: CVE-2025-53145 Type Confusion RCE in MSMQ

Headline: Urgent patch: CVE-2025-53145 — a type‑confusion RCE in Microsoft Message Queuing (MSMQ)
Summary / lede
Microsoft has published an advisory for CVE-2025-53145 — an access‑of‑resource using incompatible type (so‑called “type confusion”) vulnerability in Windows Message Queuing (MSMQ) that can allow an authorized attacker to execute code over a network. Administrators should treat systems running MSMQ as high priority for review and immediate remediation: apply Microsoft’s update, block/limits MSMQ exposure, or disable MSMQ where it isn’t required.
Why this matters

• MSMQ remains present in many Windows Server and some workstation deployments (including legacy and vertical‑industry apps). When a messaging service like MSMQ can be driven to misinterpret memory or objects, attackers can often convert that into memory corruption and remote code execution — i.e., full compromise of the host. Microsoft’s advisory for CVE-2025-53145 explicitly links the issue to type confusion and network‑accessible code execution.
• Type confusion is a well‑understood class of weakness: it occurs when code treats a resource (pointer, object, buffer) as a different — incompatible — type than it was allocated for; in memory‑unsafe languages (C/C++) that often leads to out‑of‑bounds access, crashes, or code execution. Mapping the CVE to CWE‑843 helps explain the mechanism and risk.
• MSMQ vulnerabilities have been a recurring theme in recent Microsoft advisories and Patch Tuesday rollups; the 2025 patch stream has included multiple MSMQ fixes, illustrating the service’s attack surface. Administrators should not assume MSMQ is benign just because it is “old” — legacy services are frequently targeted because they run unattended in many environments. (cybersecurity-help.cz, app.opencve.io)

What Microsoft says (short)
Microsoft’s entry for CVE‑2025‑53145 (Security Update Guide / MSRC) summarizes the flaw as "Access of resource using incompatible type ('type confusion') in Windows Message Queuing" and notes that it allows an authorized attacker to execute code remotely. Read the official advisory and apply the vendor patch as the primary remediation.
Attack vector and prerequisites (what an attacker needs)

• Network vector: MSMQ is a networked service. Many MSMQ vulnerabilities can be triggered by specially crafted messages or network packets sent to the service; in general, network accessibility of the MSMQ service increases risk.
• “Authorized attacker”: Microsoft’s wording indicates the attacker needs some form of authorization or ability to interact with MSMQ (for example, a valid account, an application that can submit messages, or access via a network path). That means anonymous Internet scans are less likely to succeed unless the service is exposed with weak or no authentication — but in poorly segmented environments an attacker with foothold or an application account may be enough. Always treat “authorized but remote” as high seriousness in enterprise contexts.
• Impact if exploited: remote code execution (RCE) — full system compromise is possible.

Technical background (concise)
Type confusion (CWE‑843) happens when code allocates or initializes a resource as one type and later accesses it as a different, incompatible type. In unmanaged languages this mismatch can let attackers read or write out of intended bounds, corrupt control data, and pivot to execution. Applied to MSMQ, a crafted message or request that forces the message parser/handler to reinterpret internal data structures can lead to memory corruption and execution of attacker controlled code paths. The CWE page gives concrete examples and explains why such bugs often lead to severe consequences.
How to quickly assess exposure in your environment
1) Find hosts with the MSMQ service installed or enabled

• On Windows Server (PowerShell): Get-WindowsFeature MSMQ
  If any MSMQ feature shows as Installed, that server has MSMQ components.
• On Windows (client or server) you can also check the service: Get-Service -Name MSMQ or Get-Service -Name Mqsvc (service name varies; list msmq).
  Example:
• PowerShell: Get-Service -Name msmq*
  These commands help you quickly inventory servers with the service present.

2) Find hosts listening on MSMQ ports

• MSMQ uses TCP/UDP 1801 and several RPC ports (2101/2103/2105 etc. and RPC discovery on 135). If you see 1801 open to untrusted networks, that’s an urgent red flag. Microsoft documents MSMQ port usage (TCP 1801, RPC 135 and 2xxx, UDP 3527 etc.). Block or restrict these at network edge/host firewall until patched.

3) Search your SIEM / EDR for recent unusual MSMQ traffic

• Look for spikes of traffic to TCP 1801, unexpected inbound messages from external source IPs, or new accounts/apps sending message traffic. If you have network packet capture, look for malformed MSMQ frames.

Immediate mitigation steps (ordered, start with what’s fastest and least disruptive)
1) Patch first (recommended)

• Apply Microsoft’s security update for CVE‑2025‑53145 to all affected Windows builds as soon as testing permits. This is the only mitigation that fully eliminates the underlying defect. Check Microsoft Update, Windows Update for Business/WSUS, or Microsoft Update Catalog for your KB/patch bundles.

2) If you cannot patch immediately: reduce exposure

• Block inbound access to MSMQ ports at network edges and host firewalls (TCP/UDP 1801, RPC discovery 135 and 2xxx RPC ports, UDP 3527). Microsoft has recommended firewall blocking of MSMQ ports as a mitigation in past advisories and KB articles. Note: blocking all MSMQ ports will break applications that legitimately depend on it. Put mitigations in place only after impact analysis. (learn.microsoft.com, ftp.zx.net.nz)

3) If MSMQ is not required: disable/uninstall it

• On servers where MSMQ is unused, remove the Windows feature (fast and effective). Examples:
• Server PowerShell: Get-WindowsFeature MSMQ (to discover) and then Remove-WindowsFeature MSMQ‑Server (or Uninstall-WindowsFeature /Restart).
• Client: DISM /Online /Disable-Feature /FeatureName:MSMQ-Server /Remove (or use Windows Features UI).
• Removing the feature eliminates the attack surface quickly, with minimal technical complexity where MSMQ is truly unused.

4) Apply network segmentation and least privilege

• Ensure only known, trusted hosts and applications can reach MSMQ endpoints. Use ACLs, host firewall rules, and network segmentation to limit which systems and service accounts can submit messages. Where MSMQ authentication/AD integration is used, review queue permissions.

Detection and hunting guidance (samples)

• Host‑level checks
• PowerShell inventory: Get‑Service -Name msmq ; Get‑WindowsFeature MSMQ* (server) ; Get‑WindowsOptionalFeature -Online | ? FeatureName -match "MSMQ".
• Check for the process/service: mqsvc.exe / Message Queuing service state.
• Network/SIEM searches (examples)
• Splunk / generic: index=netfw OR index=network (dest_port=1801 OR (dest_port>=2101 AND dest_port<=2110) OR dest_port=3527) | stats count by src_ip,dest_host
• Detect a sudden increase in new external IPs sending to port 1801, or spikes in malformed application‑layer payloads.
• EDR/Host indicators
• After a suspected exploit, look for unusual child processes of service hosts (e.g., one-time cmd.exe, powershell, rundll32 spawning from a service account that normally only runs MSMQ).
• Note: no public exploit detailing CVE‑2025‑53145 should be tested on production systems. If you need to hunt actively, do so with controlled labs and forensic capture.

Operational checklist for IT teams (step‑by‑step)

• Identify all hosts with MSMQ installed (PowerShell + CMDB).
• Prioritize patching by exposure and criticality (Internet‑facing, DMZ, customer‑facing services, or hosts running mission‑critical workloads first).
• If patch cannot be immediately applied:
• Block inbound MSMQ ports to untrusted networks at perimeter and host firewalls.
• Review queue permissions and disable unauthenticated submission endpoints.
• For systems that don’t require MSMQ, remove the Windows feature or stop and disable the MSMQ service and monitor for impact. (learn.microsoft.com, serverfault.com)
• After patching, confirm via vulnerability scanner, patch management reports, or Microsoft Update Catalog that the KB is applied.
• Optionally, schedule mitigation validation: run regression tests for applications that use MSMQ to confirm no breaking changes.

Communications & governance

• Inform application owners and business stakeholders: remediation may require service restarts and/or removal of features. Provide a date/timeline for emergency patch rollouts.
• If you operate a SOC, add detection rules for ports 1801/3527 and new or anomalous MSMQ traffic. Monitor for post‑patch anomalies (unexpected reconfigurations, restarts, or crashes).

Context & history — why MSMQ keeps showing up in advisories
MSMQ is an old, durable Windows component used in many legacy and vertical applications. Over the last few years Microsoft and third parties have published several MSMQ CVEs and patches (multiple MSMQ CVEs were addressed in 2025's Patch Tuesday cycles). These repeated advisories underscore that older platform services with rich network interfaces remain high‑value targets for attackers and deserve deliberate inventory and remediation policies. (cybersecurity-help.cz, app.opencve.io)
Practical commands (examples)

• Inventory MSMQ (Server):
• PowerShell (server): Get-WindowsFeature MSMQ
• Inventory MSMQ (any Windows):
• PowerShell: Get-Service -Name msmq*
• Disable MSMQ (client via DISM):
• DISM /Online /Disable-Feature /FeatureName:MSMQ-Server /Remove
• Remove MSMQ (Server):
• PowerShell: Remove-WindowsFeature MSMQ‑Server -Restart
  (Always test in staging and verify exact feature names in your build — run Get‑WindowsOptionalFeature or Get‑WindowsFeature to confirm names first).

Evidence from your uploaded files (if relevant)

• In the archive you provided, forum threads and advisory summaries repeatedly warn that MSMQ vulnerabilities are often network‑accessible and that disabling MSMQ or blocking port 1801 is a practical mitigation while patches are deployed. That community guidance aligns with Microsoft’s recommended mitigations and with the risk profile described above.

Risk assessment & decision guidance

• If MSMQ is Internet‑facing or reachable from untrusted networks → treat as critical: patch immediately and block access until patched.
• If MSMQ is internal but used by critical apps → high priority: schedule rapid test/push of Microsoft’s update in your patch window; enforce network segmentation and monitoring.
• If MSMQ is unused → remove it now (lowest long‑term risk).

Sources and further reading (selected)

• Microsoft Security Response Center — CVE‑2025‑53145 advisory (MSRC / Security Update Guide). The primary vendor advisory; read and apply updates listed there.
• CWE‑843: Access of Resource Using Incompatible Type ('Type Confusion') — explanation of the root weakness class. Useful to understand how type confusion can lead to RCE.
• Microsoft KB / port documentation — MSMQ uses TCP/UDP 1801 and RPC ports; firewall blocking has historically been recommended as a mitigation for network‑accessible MSMQ weaknesses. See Microsoft port guidance and older KBs for port lists and firewall workarounds. (ftp.zx.net.nz, learn.microsoft.com)
• Independent vulnerability databases and trackers (OpenCVE / vulnerability trackers) showing MSMQ CVEs and past patch bundles for context. These illustrate the cluster of MSMQ issues in 2025 Patch cycles and help prioritize patching. (app.opencve.io, cybersecurity-help.cz)
• Your uploaded forum threads / archive (you provided) — community guidance and mitigation notes that mirror vendor guidance (patch, block, or disable where possible).

What I can do next for you

• If you’d like, I can:
• Generate a short runbook (one‑page) for your operations team with exact PowerShell/DISM commands, firewall rules, and a patch rollout checklist tailored to Server vs client fleets.
• Produce sample SIEM (Splunk/Elastic) and EDR detection rules you can deploy to hunt for pre‑ or post‑exploit indicators.
• Help triage a small list of hostnames/IPs you suspect are exposed (give me the list and I’ll return the recommended priority order and remediations).
  Tell me which you want and whether you prefer PowerShell/DISM examples tuned for Windows Server (Get‑WindowsFeature) or mixed environments.

Final, brief guidance
1) Treat CVE‑2025‑53145 as high‑priority for any machine running MSMQ: patch quickly.
2) If you cannot patch immediately, block MSMQ network exposure (TCP/UDP 1801 and related RPC ports) and/or uninstall MSMQ where it’s not needed. (ftp.zx.net.nz, learn.microsoft.com)
3) Add hunt rules for unusual traffic to MSMQ endpoints, and validate that your mitigation actions do not break legitimate message flows.
If you want the one‑page runbook or the SIEM hunting rules, say which format (Splunk, Elastic, QRadar) and whether this is for a Windows Server estate or mixed Windows clients + servers — I’ll produce them next.

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Source: MSRC Security Update Guide - Microsoft Security Response Center