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Introduction:
Nearly a year after WinRAR patched CVE-2025-8088, Russia-aligned intrusion sets including SHADOW-EARTH-066 (UAC-0226) and Earth Dahu (Gamaredon) continue to weaponize the path traversal flaw against Ukrainian organizations, with fresh exploit samples as recent as April 2026. This exposes two harsh realities: adversaries are relentlessly pragmatic, reusing what works rather than chasing novelty, and patch propagation across fleets of non-auto-updating utilities remains the true challenge. Below, we extract technical details from the TrendAI research, provide actionable commands for detection and mitigation, and outline a hardened vulnerability management strategy.
Learning Objectives:
– Understand how CVE-2025-8088 path traversal works and why it remains attractive to multiple APT clusters.
– Learn to detect exploitation artifacts using PowerShell, Sysmon, and network logs.
– Implement patch propagation and compensating controls for WinRAR and similar utility applications.
You Should Know:
1. Understanding CVE-2025-8088: The Path Traversal Flaw
This vulnerability allows a crafted .rar archive to write files outside the intended extraction directory using relative path sequences (e.g., `..\..\Windows\System32\malware.exe`). Attackers combine it with lure documents (e.g., PDF or DOCX icons) to trick users into extracting the archive, triggering payload delivery.
Step‑by‑step guide to simulate (for authorized testing only):
Linux (generate malicious RAR structure):
Create a payload (e.g., reverse shell) echo "calc.exe" > malicious.exe Use rar (install via apt install rar) to add path traversal entries rar a -ep1 -r malicious.rar malicious.exe Then manually hex-edit or use a Python script to insert "../" sequences
Python proof-of-concept (Windows target extraction):
import rarfile Victim extracts archive with rarfile or WinRAR GUI Crafted entry: "../../AppData/Roaming/Microsoft/Windows/Start Menu/Programs/Startup/payload.exe" Upon extraction, payload lands in startup folder
Mitigation: Block extraction of archives containing `..\` or `../` sequences using content inspection proxies or EDR rules.
2. Checking Your Fleet for Unpatched WinRAR Versions
WinRAR does not auto-update and falls outside WSUS/SCCM by default. Use these commands to identify vulnerable endpoints (affected: WinRAR < 7.13).
PowerShell (scan local machine):
Get-ItemProperty "HKLM:\SOFTWARE\WinRAR" -1ame "Version" -ErrorAction SilentlyContinue Or for 32-bit on 64-bit: Get-ItemProperty "HKLM:\SOFTWARE\WOW6432Node\WinRAR" -1ame "Version"
Check all installed versions across domain (requires admin rights):
$computers = Get-ADComputer -Filter | Select-Object -ExpandProperty Name
foreach ($comp in $computers) {
$version = Invoke-Command -ComputerName $comp -ScriptBlock {
(Get-ItemProperty "HKLM:\SOFTWARE\WinRAR" -1ame "Version" -ErrorAction SilentlyContinue).Version
}
if ($version -and [bash]$version -lt [bash]"7.13") {
Write-Output "$comp : $version - VULNERABLE"
}
}
Group Policy remediation: Deploy WinRAR 7.13+ via startup script or PDQ/Intune. Alternatively, use AppLocker to block older WinRAR executables.
3. Detecting Exploitation in the Wild
SHADOW-EARTH-066 evolved GIFTEDCROOK from Excel macros with plaintext Telegram C2 to in-memory DLL loading using direct NT system calls (evading user-mode hooks). Earth Dahu delivers HTA-based chains proxied via Cloudflare Workers.
Sysmon event monitoring (Event ID 1 – Process Creation):
Look for WinRAR.exe spawning unexpected child processes (cmd, powershell, wscript, mshta):
EventRecordID: ... Image: C:\Program Files\WinRAR\WinRAR.exe ParentImage: explorer.exe CommandLine: WinRAR.exe x -ibck -inul "malicious.rar" . ChildProcess: C:\Windows\System32\mshta.exe
Detection rule (PowerShell using Get-WinEvent):
$events = Get-WinEvent -FilterHashtable @{LogName='Microsoft-Windows-Sysmon/Operational'; ID=1} | Where-Object {
$_.Message -match "WinRAR.exe" -and ($_.Message -match "cmd.exe|powershell.exe|mshta.exe|wscript.exe|cscript.exe")
}
$events | Format-Table TimeCreated, Message -AutoSize
Detect direct NT system calls (advanced – requires ETW or kernel callbacks):
Monitor for `ntdll!Nt` functions called without matching user-mode API chain (e.g., `NtCreateFile` not preceded by `kernel32!CreateFile`). Use tools like Sysinternals ProcMon with stack traces or EDR with hook evasion detection.
Network detection for Cloudflare Workers proxy:
Earth Dahu C2 often resolves to `.workers.dev` domains. Hunt DNS logs:
Get-WinEvent -FilterHashtable @{LogName='Microsoft-Windows-DNS-Client/Operational'; ID=3008} |
Where-Object { $_.Message -match "\.workers\.dev" }
Block `.workers.dev` via firewall or proxy if not business-required.
4. Mitigating Without Immediate Patching
When patching cannot be pushed instantly, use application control and sandboxing.
Windows Defender Application Control (WDAC) or AppLocker:
Create a rule to block WinRAR versions < 7.13:
Get file hash of vulnerable WinRAR.exe Get-FileHash "C:\Program Files\WinRAR\WinRAR.exe" Deploy AppLocker rule via GPO: Deny execution for that hash or path
Software Restriction Policies (SRP) – legacy but effective:
Set path rule: `%ProgramFiles%\WinRAR\WinRAR.exe` – Disallowed. Then allow only the updated version path if renamed (not recommended) or use certificate rules.
Alternative archivers:
Migrate users to 7-Zip (supports .rar extraction but not creation) or Bandizip. Push via silent install:
7z1900-x64.exe /S
Sandboxing: Configure Microsoft Defender Exploit Guard to force WinRAR to run in AppContainer or as a low-integrity process.
5. Hunting GIFTEDCROOK and Earth Dahu IOCs
Full IOCs available at the TrendAI research link: https://lnkd.in/guyymBtA
Example YARA rule for GIFTEDCROOK (in-memory DLL with NT syscalls):
rule GIFTEDCROOK_NT_Syscalls {
strings:
$syscall1 = { 0f 05 } // syscall instruction
$mov_eax = { b8 ?? ?? 00 00 } // mov eax, syscall number
$nt_prefix = "NtCreateFile" wide ascii
condition:
$syscall1 and $mov_eax and $nt_prefix
}
PowerShell hunting for Earth Dahu HTA artifacts:
Get-ChildItem -Path C:\Users\\AppData\Local\Temp\ -Recurse -Include .hta |
Select-Object FullName, LastWriteTime, @{N='Content';E={Get-Content $_.FullName -Raw}} |
Where-Object { $_.Content -match "CreateObject\(" -and $_.Content -match "http" }
Process memory dump analysis: Use `rundll32.exe` or `regsvr32.exe` with unusual arguments. Capture with:
Get-Process -1ame "WinRAR" | ForEach-Object { .\procdump.exe -ma $_.Id dump_$_.Id.dmp }
6. Building a Long-Term Vulnerability Management Strategy for Utility Apps
WinRAR’s inability to auto-update mirrors risks in many apps (PDF readers, archive tools, media players). Implement a Continuous Threat Exposure Management (CTEM) program.
Automated inventory for non-MSI installs:
List all uninstall keys with no auto-update flag
Get-ChildItem "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall" |
ForEach-Object { Get-ItemProperty $_.PsPath } |
Where-Object { $_.DisplayName -match "WinRAR|7-Zip|Adobe Reader" } |
Select-Object DisplayName, DisplayVersion, Publisher
Weekly patch verification script (emailed report):
$vuln = @()
$installed = Get-WmiObject -Class Win32_Product | Where-Object {$_.Name -like "WinRAR"}
if ([bash]$installed.Version -lt "7.13.0") { $vuln += $env:COMPUTERNAME }
Send-MailMessage -To "[email protected]" -Subject "Vulnerable WinRAR hosts" -Body ($vuln -join ",") -SmtpServer smtp.domain.com
Tool substitution policy: Phase out any utility that fails to support:
– Enterprise update channels (e.g., Winget, Chocolatey, or built-in auto-update)
– Silent installation with MSI
– Group Policy configuration
Deploy Winget to force updates:
winget upgrade "WinRAR.WinRAR" --accept-package-agreements --silent
What Undercode Say:
– Key Takeaway 1: Adversaries industrialize flaws that remain effective. CVE-2025-8088 follows the same trajectory as CVE-2018-20250 – expect exploitation for years unless organizations solve the patch propagation problem for utility software.
– Key Takeaway 2: Detection must evolve beyond simple macro signatures. The shift to in-memory DLL loading via direct NT system calls (GIFTEDCROOK) and Cloudflare Workers proxying (Earth Dahu) demands behavioral monitoring and network anomaly detection, not just static IOCs.
Analysis: The post correctly reframes vulnerability management from “find and fix” to “find, fix, and verify propagation across every endpoint.” Many teams celebrate patching a central server but ignore the long tail of user workstations where WinRAR lives. The attackers know this – that’s why they keep using the same flaw. Moreover, the technical evolution of GIFTEDCROOK shows a clear investment in evasion: dropping macros for direct syscalls reduces detection by traditional EDR hooks. Defenders must adopt kernel-level monitoring (e.g., Sysmon with driver updates, ETW TI feeds) and treat utility applications as a distinct risk category with compensating controls like application whitelisting or forced sandboxing. The two unrelated clusters converging on the same flaw without shared infrastructure underscores that vulnerability markets are driven by returns on investment, not novelty. Organizations that fail to treat WinRAR and similar tools as a critical attack surface will continue to be low-hanging fruit.
Prediction:
– -1 Continued exploitation of CVE-2025-8088 for at least another 12–18 months, as many enterprises still have not pushed WinRAR 7.13 across all endpoints.
– -1 Rise of “patch-resistant” malware that specifically targets software without auto-update mechanisms, with threat actors developing automated scanners for unpatched WinRAR, WinZip, and Adobe Acrobat Reader.
– +1 Increased adoption of CTEM (Continuous Threat Exposure Management) and application inventory tools among mature security teams, driven by visibility into these long-tail vulnerabilities.
– -1 More supply chain attacks leveraging path traversal flaws in archiving libraries (e.g., libarchive, SharpCompress) used by backup and file-sharing SaaS products.
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Reported By: [Jpcastro Cybersecurity](https://www.linkedin.com/posts/jpcastro_cybersecurity-threatintelligence-vulnerabilitymanagement-share-7469856950063742977-H4xL/) – Hackers Feeds
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