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HighCISA KEVExploited in the wildPublic exploit

WinRAR ACE archive path traversal arbitrary file write

IdentifiersCVE-2018-20250CWE-22· Improper Limitation of a Pathname…

CVE-2018-20250 is a path traversal vulnerability in WinRAR prior to and including version 5.61 in its handling of ACE archives via UNACEV2.dll. By crafting the ACE filename field with specific traversal or absolute-path patterns, an attacker can cause WinRAR to ignore the user-selected extraction directory and write extracted files to arbitrary filesystem locations. In practical exploitation, malicious archives have been used to drop payloads into autostart locations such as the Windows Startup folder or application-specific load paths such as Microsoft Word’s add-in directory, resulting in execution of attacker-controlled code when the user logs in or launches the affected application.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows arbitrary file write outside the intended extraction directory. This can be leveraged for persistence and, depending on the chosen destination path, effective code execution on the victim host. Observed campaigns used the flaw to place scripts, batch files, HTA files, LNK files, or DLL/add-in payloads into locations that are automatically executed by Windows or common applications. The vulnerability therefore enables initial access, malware installation, persistence, and follow-on compromise of the affected system.

Mitigation

If you can’t patch tonight, do this now.

Until patching is complete, block or quarantine ACE-containing archives and untrusted RAR/ACE attachments from email and web downloads, especially in phishing-prone workflows. Restrict users from extracting archives from untrusted sources, monitor for archive extraction writing into sensitive paths such as Startup folders and Office add-in directories, and use application control to prevent execution of newly dropped scripts, HTA files, LNK-launched payloads, and unauthorized add-ins from user-writable locations. Detection logic should not focus only on Startup-folder writes, since attackers can choose alternate autorun or application load paths.

Remediation

Patch, then assume compromise.

Upgrade WinRAR to a fixed version. The provided content states the issue was fixed in WinRAR 5.70; vulnerable versions are prior to and including 5.61. Organizations should ensure ACE archive handling is no longer performed by the vulnerable UNACEV2.dll component and verify that all endpoints are running a patched WinRAR release. Because WinRAR historically lacked an auto-update mechanism, remediation should include explicit enterprise-wide inventorying and manual or managed upgrade of installed versions.
PUBLIC EXPLOITS

Exploits

1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos (2 hidden).

VALID 1 / 3 TOTALView more in app
CVE-2018-20250MaturityPoCVerified exploit

This repository provides a Python exploit script (exp.py) that generates a malicious RAR archive designed to exploit a path traversal/code execution vulnerability in WinRAR (as described in Check Point's research). The script takes an attacker-supplied executable (e.g., calc.exe) and crafts a RAR file (test.rar) that, when extracted by a victim using a vulnerable version of WinRAR, will drop the executable into the victim's Windows Startup folder (C:\C:C:../AppData/Roaming/Microsoft/Windows/Start Menu/Programs/Startup/hi.exe). This ensures the payload will execute on the next system reboot. The archive also contains decoy files (hello.txt, world.txt) to appear innocuous. The exploit requires the attacker to provide the payload and specify the target path. The repository consists of the main exploit script (exp.py), two decoy text files, and a README.md with usage instructions and background. No network endpoints are involved; the attack vector is local, relying on user interaction with the malicious archive.

WyAtuDisclosed Feb 22, 2019pythonlocal
EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
WinRARWinrarapplication

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What this page doesn’t show

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Exposure mapping

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Threat actor evidence2

Every observed campaign linking this CVE to a named adversary.

Associated malware1

Malware families riding this exploit, with evidence and IOCs.

Detection signatures1

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity1

Community discussion across Reddit, Mastodon, and other social sources.