CVE-2025-6218: Finding the Achilles’ Heel of WinRAR
- Javier Conejo del Cerro
- hace 1 día
- 4 Min. de lectura
In every ancient battle, even the mightiest warrior fell when an enemy discovered the one weak point in his armor. The same pattern now repeats in the digital age. WinRAR — a tool relied upon by millions of Windows users for decades — carries its own Achilles’ heel: CVE-2025-6218, a path traversal flaw allowing attackers to place malicious files in privileged locations and execute code on the next reboot.
Despite a fix issued in June 2025, the vulnerability remains under active exploitation by multiple threat groups. And just like Troy’s enemies exploiting a single exposed tendon, attackers today weaponize this weakness through spear-phishing and booby-trapped RAR files, slipping their payloads past the gates of unsuspecting users and embedding themselves deep inside the system.
This is not theoretical. It is happening now, and at scale.
Phase 1: Identifying the Weak Spot — The Achilles’ Heel Emerges
Path traversal vulnerabilities are not new, but CVE-2025-6218 strikes at a uniquely dangerous part of Windows systems: the ability to plant files exactly where they should never be, such as the Startup folder or Office template directories.
If abused, even a simple RAR archive becomes a well-aimed spear.
RARLAB patched the flaw in WinRAR 7.12, limiting the impact to Windows builds only. Platforms like Unix and Android remain unaffected. Yet as with Achilles’ armor, the flaw is only harmless once repaired — and countless users and organizations continue running outdated versions, unaware their systems carry an exposed tendon.
Phase 2: Victims in the Battlefield — Users Who Never Saw the Spear
The victims of this campaign are not specialized targets.
They are ordinary Windows users:
people who open RAR attachments they trust,
users who visit compromised web pages containing malicious archives,
organizations relying on outdated WinRAR versions still deployed across endpoints.
No administrator privileges are needed.
No exploit kits.
No advanced techniques on the user’s part.
Just a single interaction — opening a file — is enough to expose the system.
Attackers exploit this user behavior because it mirrors a battlefield mistake: lowering one’s shield for a moment, never expecting an ambush. In this case, the ambush is file placement in sensitive directories, executed silently and without noticeable symptoms.
Phase 3: The Spear Strikes — How the Breach Happens
The breach begins with a simple RAR file that looks harmless but contains an embedded path traversal payload. Once opened:
Malicious files are dropped into privileged paths like:
the Windows Startup directory,
Microsoft Word’s global template Normal.dotm path.
These files leverage Windows’ own behavior:
Startup executables run automatically on the next login.
Normal.dotm loads every time Word opens, bypassing macro-blocking policies.
Threat actors use these paths to deploy:
backdoors,
keyloggers,
screenshot capture tools,
RDP credential harvesters,
file exfiltration mechanisms.
Multiple threat groups — including GOFFEE, Bitter and Gamaredon — chain CVE-2025-6218 with other WinRAR flaws such as CVE-2025-8088, intensifying the damage.
In the case of Bitter APT, malicious RAR archives drop modified Word templates to establish persistence and then deploy a C# trojan that communicates with a C2 domain for full surveillance and remote control.
Gamaredon, targeting Ukrainian military and government entities, uses the flaw to deploy Pteranodon and even GamaWiper, marking a shift from espionage toward destructive operations.
The path traversal exploit is not just an entry point — it is the well-placed spear that causes the entire defensive structure to collapse.
Phase 4: Expanding the Siege — Multi-Group Exploitation
The exploitation of CVE-2025-6218 is coordinated and widespread:
GOFFEE (Paper Werewolf) is observed combining this flaw with other vulnerabilities for intrusions in Russia.
Bitter (APT-C-08) uses it to achieve persistence and drop trojans across South Asian targets.
Gamaredon, known for aggressive activity against Ukrainian institutions, chains the vulnerability to deploy espionage malware and wipers.
Each group adopts the vulnerability differently, but all share a goal:
turn an overlooked weakness into a decisive victory.
Their tactics resemble a multi-front siege:
One breach, many armies.
Phase 5: Defending the Gates — What Organizations Must do
Just as ancient civilizations reinforced weak walls with stone and bronze, modern defenders must reinforce their systems with patches and controls. CISA has added CVE-2025-6218 to its Known Exploited Vulnerabilities (KEV) list and mandated action for all federal agencies by December 30, 2025.
Recommended measures include:
Updating WinRAR to version 7.12 immediately.
Blocking suspicious RAR archives at email and gateway levels.
Hardened macro policies and continuous monitoring of Word’s template paths.
Monitoring for Windows path traversal exploitation attempts.
Detecting unauthorized file creation in Startup folders.
Strengthening endpoint controls to detect malicious droppers and persistence mechanisms.
A single unpatched endpoint can serve as an exposed heel for the entire enterprise.
CVE-2025-6218 proves once again that attackers do not need overwhelming force — only precision and timing. The flaw offers adversaries a way to weaponize harmless-looking archives into silent execution chains that reach deep into critical system paths.
Like Achilles, WinRAR’s strength depended on every part of its armor being intact. The moment one piece failed, adversaries exploited it ruthlessly.
The lesson remains timeless:
Patch the heel before the spear finds it.
If organizations act quickly, the vulnerability becomes harmless.
If they ignore it, they stand on the battlefield with their tendon exposed.
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