UAC-0099 Using WinRAR Exploit to Target Ukrainian Firms with LONEPAGE Malware
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2023-38831 | Code Execution in RARLAB WinRAR via Crafted ZIP File/Folder Name Confusion RARLAB WinRAR before 6.23 mishandles ZIP archives that contain a benign file (such as a JPG) alongside a folder with the same name, causing the folder's contents - which can include malicious executable files - to be processed when the user merely attempts to view the benign file. By sending a crafted ZIP archive, an attacker gains arbitrary code execution on the victim's machine with the user's privileges. Because the flaw is local (AV:L) and requires user interaction, risk is limited to Windows systems running an unpatched copy of WinRAR, while machines without the tool are unaffected. The bug was actively exploited in the wild from April through October 2023, including by government-backed actors (APT28), SideCopy attacks on Indian government entities, ransomware operations, and trading-account theft campaigns, and it was added to CISA's Known Exploited Vulnerabilities catalog on 2023-08-24. Do: Upgrade all Windows systems running WinRAR to version 6.23 or later, which fixes this flaw; if patching is not immediately possible, treat ZIP files from untrusted sources with caution and check archives for duplicate file/folder names before opening. Given KEV listing with known ransomware use and public proof-of-concept exploits, hunt for compromise by reviewing whether unexpected executables or scripts ran when ZIP archives were opened, and apply vendor mitigations per CISA's required action or discontinue use if mitigations are unavailable. | 7.8 | 98% | KEV ransomware PoC ×4 |
| masshundreds of millions of users/installations worldwide (WinRAR is one of the most widely installed Windows archive utilities) |
Full article391 words · extracted from thehackernews.com · click to collapse
Ravie LakshmananDec 22, 2023Malware / Cyber Attack
The threat actor known as UAC-0099 has been linked to continued attacks aimed at Ukraine, some of which leverage a high-severity flaw in the WinRAR software to deliver a malware strain called LONEPAGE.
"The threat actor targets Ukrainian employees working for companies outside of Ukraine," cybersecurity firm Deep Instinct said in a Thursday analysis.
UAC-0099 was first documented by the Computer Emergency Response Team of Ukraine (CERT-UA) in June 2023, detailing its attacks against state organizations and media entities for espionage motives.
The attack chains leveraged phishing messages containing HTA, RAR, and LNK file attachments that led to the deployment of LONEPAGE, a Visual Basic Script (VBS) malware that's capable of contacting a command-and-control (C2) server to retrieve additional payloads such as keyloggers, stealers, and screenshot malware.
"During 2022-2023, the mentioned group received unauthorized remote access to several dozen computers in Ukraine," CERT-UA said at the time.
The latest analysis from Deep Instinct reveals that the use of HTA attachments is just one of three different infection chains, the other two of which leverage self-extracting (SFX) archives and booby-trapped ZIP files. The ZIP files exploit the WinRAR vulnerability (CVE-2023-38831, CVSS score: 7.8) to distribute LONEPAGE.
In the former, the SFX file houses an LNK shortcut that's disguised as a DOCX file for a court summons while using the icon for Microsoft WordPad to entice the victim into opening it, resulting in the execution of malicious PowerShell code that drops the LONEPAGE malware.
The other attack sequence uses a specially crafted ZIP archive that's susceptible to CVE-2023-38831, with Deep Instinct finding two such artifacts created by UAC-0099 on August 5, 2023, three days after WinRAR maintainers released a patch for the bug.
"The tactics used by 'UAC-0099' are simple, yet effective," the company said. "Despite the different initial infection vectors, the core infection is the same — they rely on PowerShell and the creation of a scheduled task that executes a VBS file."
The development comes as CERT-UA warned of a new wave of phishing messages purporting to be outstanding Kyivstar dues to propagate a remote access trojan known as Remcos RAT. The agency attributed the campaign to UAC-0050.
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