CVE-2023-3181
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedThe C:\Program Files (x86)\Splashtop\Splashtop Software Updater\uninst.exe process creates a folder at C:\Windows\Temp~nsu.tmp and copies itself to it as Au_.exe. The C:\Windows\Temp~nsu.tmp\Au_.exe file is automatically launched as SYSTEM when the system reboots or when a standard user runs an MSI repair using Splashtop Streamer’s Windows Installer. Since the C:\Windows\Temp~nsu.tmp folder inherits permissions from C:\Windows\Temp and Au_.exe is susceptible to DLL hijacking, standard users can write a malicious DLL to it and elevate their privileges.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThe Splashtop Software Updater creates a folder at C:\Windows\Temp~nsu.tmp and copies itself as Au_.exe, which automatically runs as SYSTEM on system reboot or when a standard user runs an MSI repair. Since the folder inherits weak permissions from C:\Windows\Temp and Au_.exe is vulnerable to DLL hijacking, standard users can place a malicious DLL in the folder to achieve privilege escalation to SYSTEM.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 2.4.0.1< 1.3.0.0< 3.5.6.0< 3.5.8.0< 3.5.8.0< 3.5.6.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify installed Splashtop productsOpen Control Panel > Programs and Features, or run 'Get-ItemProperty HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\* | Select-Object DisplayName, DisplayVersion' to list installed software and look for Splashtop entries.Affected if Any Splashtop Mirroring360 Receiver, Sender, Streamer, or Splashtop for RMM is installed with a version below the affected ranges (Receiver < 2.4.0.1, Sender < 1.3.0.0, Streamer < 3.5.6.0, Splashtop < 3.5.6.0 or < 3.5.8.0, Splashtop for RMM < 3.5.8.0).
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Check for the vulnerable temp folderOpen File Explorer and navigate to C:\Windows\Temp or use command 'dir C:\Windows\Temp~nsu.tmp' in an elevated or standard command prompt.Affected if The folder C:\Windows\Temp~nsu.tmp exists on the system.
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Check for the Au_.exe executableUse command 'dir C:\Windows\Temp~nsu.tmp\Au_.exe' or 'Get-ChildItem C:\Windows\Temp~nsu.tmp\Au_.exe' to verify the file exists.Affected if The file Au_.exe exists in the C:\Windows\Temp~nsu.tmp directory.
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Check for Splashtop Software Updater serviceOpen Services (services.msc) and look for 'Splashtop Software Updater' or run 'Get-Service | Where-Object {$_.DisplayName -like "*Splashtop*Updater*"}'Affected if The Splashtop Software Updater service is installed and set to run.
A system is affected if any Splashtop product version from the affected list is installed AND the C:\Windows\Temp~nsu.tmp folder with Au_.exe exists, allowing standard users to perform DLL hijacking for SYSTEM privilege escalation.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped1.3.0.02.4.0.13.5.6.0
Remove the C:\Windows\Temp~nsu.tmp folder and Au_.exe file, disable or uninstall the Splashtop Software Updater service, and apply vendor patches when available. Restrict write access to the Windows Temp directory as a defense-in-depth measure.
Splashtop products should be upgraded to their respective minimum fixed versions: Mirroring360 Receiver 2.4.0.1+, Mirroring360 Sender 1.3.0.0+, Splashtop 3.5.6.0+/3.5.8.0+, Splashtop For RMM 3.5.8.0+, Streamer 3.5.6.0+
- Identify the installed Splashtop product (Mirroring360 Receiver, Mirroring360 Sender, Splashtop, Splashtop For RMM, or Streamer) by checking Add/Remove Programs or the program's About section
- Download the latest version from the official Splashtop website or your organization's software distribution point
- For Mirroring360 Receiver: Upgrade to version 2.4.0.1 or later
- For Mirroring360 Sender: Upgrade to version 1.3.0.0 or later
- For Splashtop: Upgrade to version 3.5.6.0 or later (or 3.5.8.0 or later depending on your branch)
- For Splashtop For RMM: Upgrade to version 3.5.8.0 or later
- For Streamer: Upgrade to version 3.5.6.0 or later
- After upgrade, verify the C:\Windows\Temp\~nsu.tmp folder is no longer created with insecure permissions
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-3181 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2023-3181 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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