This week, Google’s Threat Intelligence Group and several security outlets highlighted a familiar but uncomfortable story: a critical WinRAR vulnerability, tracked as CVE-2025-8088, is still being actively exploited by both state-backed and financially motivated threat actors, even though a patch has been available since July 2025.
The attack pattern is simple and effective:
- A malicious .rar archive is sent via phishing or file-sharing.
- The victim extracts it using a vulnerable version of WinRAR (7.12 or earlier).
- Because of a path traversal flaw, hidden payloads can be written into sensitive locations like the Windows Startup folder.
- On the next logon or reboot, the payload launches automatically, giving the attacker persistence on that endpoint.
In other words, “just open this archive” can quietly become “you now have malware that runs every time the machine starts.”
In this post, we are not going to reverse engineer WinRAR. Instead, we will look at what this incident says about:
- How “free” or “one-off” utilities behave on Windows endpoints.
- Why n-day vulnerabilities like this remain so popular with attackers.
- How least privilege and controlled elevation tools like Elevator for Windows help you contain the damage when something like this slips through.
What is CVE-2025-8088 in plain English?
CVE-2025-8088 is a path traversal vulnerability in WinRAR on Windows (versions 7.12 and earlier). By abusing NTFS Alternate Data Streams (ADS) inside a crafted archive, attackers can trick WinRAR into extracting files outside the expected directory, including directly into the user’s Startup folder.
Security researchers and Google GTIG have observed multiple campaigns using this to drop:
- Malicious .lnk, .bat or .hta files into the Startup folder.
- Remote access trojans (RATs) and info-stealers like XWorm and AsyncRAT.
WinRAR’s vendor, RARLAB, fixed the issue in WinRAR 7.13, released in July 2025. But many users and organisations are still on older builds, especially where WinRAR is a “trial forever” utility that people installed years ago and never think about updating.
Why this is a textbook “n-day” problem
From an attacker’s perspective, this is almost the perfect n-day vulnerability:
- The bug is public and well understood.
- Exploit code and techniques are widely documented.
- Many endpoints still run vulnerable versions because updates are not automatic.
Google notes that government-backed groups linked to Russia and China, as well as various cybercrime operators, continue to use CVE-2025-8088 in real campaigns.
This is the critical point for Windows admins:
The biggest risk is not always the brand-new zero-day. It is the old, patched bug still present on endpoints because “it’s just a utility” and no one owns it.
What it tells us about “just a utility” on Windows endpoints
WinRAR is a perfect example of how “non-critical” utilities behave in real estates:
- Installed everywhere, managed nowhere. Users install it themselves to open a one-off archive and then keep using it indefinitely.
- No automatic updates. If IT is not pushing a newer version, it will sit on 7.12 forever.
- Per-user, not per-estate. It does not always show up in your “official” software list, especially on BYOD or loosely managed laptops.
We have seen similar patterns before:
- In our post on the Samsung Magician vulnerability, the issue was an SSD management tool that quietly ran with high privileges.
- In our recent Office zero-day article, the initial foothold was a malicious document, but the real damage depended on the user’s privileges on Windows.
WinRAR adds another angle: a popular third-party tool that many admins did not explicitly approve or manage, but that still has access to the user’s file system and can be abused to plant persistence.
Local admin makes this story a lot worse
CVE-2025-8088 does not require the user to be a local admin. A standard user extracting a malicious archive with a vulnerable version is enough to get code into Startup.
However, what happens after the payload launches depends heavily on local privileges:
- If the user is a standard user, the malware’s first job is usually to look for a privilege escalation path.
- If the user is a local admin, the malware can immediately:
- Tamper with endpoint protection.
- Install additional services and drivers.
- Create new accounts or change local security settings.
This is the same pattern we have discussed in:
- Make This the Year You Remove Local Admin Rights on Windows (For Real)
- Five Myths About Removing Local Admin Rights on Windows
Removing local admin does not magically fix vulnerable software, but it dramatically reduces how far a WinRAR-style foothold can go on that first machine.
Three practical actions for Windows admins this week
1. Find and fix vulnerable WinRAR installs
Start with visibility:
- Use your software inventory tools (Intune, SCCM, Tanium, etc.) to find machines with WinRAR ≤ 7.12.
- Where possible, upgrade to 7.13 or later, or remove WinRAR if it is not needed.
- Watch for “shadow installs” in user profiles or portable versions on network shares.
You do not need to treat WinRAR as a crown jewel, but you do need to make sure you are not leaving known-vulnerable versions lying around.
2. Tighten the rules around “user-installed utilities”
WinRAR is a good prompt to revisit your approach to user-installed tools:
- Clarify which utilities are approved and packaged centrally vs “install whatever you like”.
- Use your endpoint management platform to offer safe alternatives (e.g. a centrally maintained archiver).
- Consider using application control or allow-listing to keep unknown utilities out of sensitive devices.
This does not have to be draconian. Even a simple “request this utility from IT, we’ll package and patch it” model is better than hundreds of unmanaged installs.
3. Treat least privilege as your damage limiter
Finally, use incidents like this to strengthen your least privilege story:
- Reduce the number of users in the local Administrators group.
- Use platform features like Windows 11 Administrator Protection and Intune EPM where they fit.
- Handle the stubborn apps with controlled elevation instead of giving users full admin rights forever.
This is exactly the gap that Elevator for Windows is designed to fill.
Where Elevator fits in
In many organisations, the reason people still have local admin looks something like this:
- “I need admin to install tools like WinRAR, 7-Zip, and a few other utilities.”
- “This old app only behaves if I run it as admin.”
Elevator lets you turn those into controlled, per-app elevation instead of full-time admin:
- Users run as standard users all day.
- You define a short list of applications that are allowed to run with admin rights.
- Elevator elevates just those executables, not the entire user session.
- Every elevation is logged, so you can see which tools actually need admin and adjust over time.
That means:
- You can keep users out of the local Administrators group.
- You can still support the odd legacy or specialist app that needs extra rights.
- If a malicious archive or document does slip through, it lands in a standard-user context, not a permanent admin one.
WinRAR’s CVE-2025-8088 is a reminder that attackers do not always need new zero-days. They are very happy with “old, patched bugs” living in utilities that no one quite owns. Patching those is essential. Making sure the user behind them is not a full local admin is how you keep a bad day from becoming a breach.
If you are rethinking local admin this quarter, we would love you to try Elevator on a handful of machines and see how it fits into your least-privilege plan for Windows.
