# CVE-2023-38831: Russian APTs Target Ukraine via WinRAR Flaw

> Russian threat actors are exploiting the CVE-2023-38831 WinRAR vulnerability to target Ukrainian government and military entities for data theft.

- Published: 2026-06-09T17:01:57.000Z
- Severity: high
- Category: Threat Intel
- Tags: CVE-2023-38831, WinRAR, APT28, Sandworm, Ukraine
- Author: Runtime Rebel Intel
- Primary source: https://www.darkreading.com/vulnerabilities-threats/russian-groups-winrar-flaw-ukrainian-orgs
- Canonical: https://runtimerebel.com/blog/cve-2023-38831-russian-apts-target-ukraine-via-winrar-flaw

## Key points

- Russian threat actors are targeting Ukrainian military and government entities to conduct cyberespionage and exfiltrate sensitive strategic data.
- These campaigns exploit CVE-2023-38831 within WinRAR versions prior to 6.23 to execute malicious code via specially crafted ZIP archives.
- Organizations must update WinRAR to version 6.23 or later and implement strict email attachment filtering to block suspicious archive files.

Recent intelligence reports indicate that Russian state-sponsored actors have intensified their operations against Ukrainian infrastructure by weaponizing a previously patched vulnerability in the WinRAR archiving utility. According to [Dark Reading](https://www.darkreading.com/vulnerabilities-threats/russian-groups-winrar-flaw-ukrainian-orgs), at least two distinct campaigns have been identified targeting government and military personnel with decoy documents designed to trigger [CVE-2023-38831](/cve/cve-2023-38831).

## Technical Analysis of the WinRAR Logic Flaw

[CVE-2023-38831](https://nvd.nist.gov/vuln/detail/CVE-2023-38831) is a logic vulnerability that occurs when WinRAR processes a ZIP archive containing a file and a folder with identical names. When a user double-clicks the decoy file (often a benign image or PDF), the application incorrectly attempts to execute a malicious script or executable located within the adjacent folder. This [RCE](/glossary#rce) primitive allows attackers to bypass security warnings by disguising malicious payloads as harmless documents.

In the observed campaigns, attackers use [Phishing](/glossary#phishing) emails to deliver these weaponized archives. Once the user interacts with the archive, the hidden payload executes, typically initiating a [C2](/glossary#c2) connection to facilitate data exfiltration or further [Lateral Movement](/glossary#lateral-movement) within the target network. The simplicity of the exploit makes it highly effective for an [APT](/glossary#apt) seeking to gain an initial foothold without relying on complex memory corruption techniques.

### APT28 Targeted Phishing Campaigns and Attribution

The activity has been attributed to several known entities, most notably [APT28](https://en.wikipedia.org/wiki/APT28) (also known as Fancy Bear) and [Sandworm](https://en.wikipedia.org/wiki/Sandworm_(hacker_group)). These groups have a long history of targeting Ukrainian interests to support Russian strategic objectives. In these recent instances, the lures often involve military-themed documents or administrative notices aimed at high-ranking officials.

By leveraging this specific [CVE](/glossary#cve), these actors can automate the compromise of workstations that have neglected routine software updates. While the flaw was patched in July 2023, the persistence of its use highlights a significant gap in patch management across targeted sectors. Security teams should prioritize identifying systems where legacy versions of WinRAR are still installed to prevent successful exploitation.

## Detection and Remediation Strategies

Defenders must move beyond basic signature-based detection to effectively identify these threats. To successfully **detect CVE-2023-38831 exploit** attempts, [SOC](/glossary#soc) teams should monitor for unusual process spawning from WinRAR.exe, particularly instances where `cmd.exe` or `powershell.exe` are initiated directly from the archiver utility.

### WinRAR 6.23 Patch Guidance and Mitigation

The primary defense against this threat is the immediate deployment of current software versions. Following official **WinRAR 6.23 patch guidance**—or upgrading to any version later than 6.23—eliminates the logic error used to trigger the exploit. In addition to patching, organizations should consider the following controls:

*   **Email Filtering:** Block or quarantine incoming emails containing .zip, .rar, or .7z archives from external or untrusted sources.
*   **Endpoint Monitoring:** Use [EDR](/glossary#edr) tools to flag the creation of temporary folders by WinRAR that contain executable files with extensions mismatched to their headers.
*   **User Awareness:** Train personnel to avoid opening compressed files from unsolicited communications, even if the file names appear relevant to their daily operations.

Collecting and analyzing [IoC](/glossary#ioc) data from these campaigns, such as specific command-line arguments and known malicious IP addresses, will further strengthen an organization's [Zero Trust](/glossary#zero-trust) posture against state-sponsored intrusions.

**Related:** [APT28 Targets Ukraine and NATO Allies with New PRISMEX Malware](/blog/apt28-targets-ukraine-and-nato-allies-with-new-prismex-malware), [APT28 Targets Ukraine via CVE-2024-45519 Zimbra Exploit](/blog/apt28-targets-ukraine-via-cve-2024-45519-zimbra-exploit)

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AI-generated analysis from the primary source above; not human-reviewed before publication — verify anything operational against the original (https://runtimerebel.com/editorial). Quote with attribution and a link to the canonical URL: https://runtimerebel.com/blog/cve-2023-38831-russian-apts-target-ukraine-via-winrar-flaw