malicious file Archives

Winsage

July 2, 2025

Windows Shortcut (LNK) Malware Strategies

There has been a significant increase in the exploitation of Windows shortcut files (LNK files) for malware delivery, with malicious LNK samples rising from 21,098 in 2023 to 68,392 in 2024. LNK files, identifiable by their .lnk extension, allow users to access files and applications easily, but can also execute malicious content. Key fields in LNK files that indicate malicious intent include LINKTARGETIDLIST (99.53% of malicious LNK files), RELATIVEPATH (75.49%), and COMMANDLINEARGUMENTS (35.52%). LNK malware is categorized into four types: LNK exploits, malicious file execution, in-argument script execution, and overlay content execution. Indicators of compromise for LNK malware include specific SHA256 hashes for various samples.

Winsage

June 18, 2025

XDSpy Threat Actors Leverages Windows LNKs Zero-Day Vulnerability to Attack Windows System Users

A cyber espionage campaign attributed to the XDSpy threat actor has been discovered, exploiting a zero-day vulnerability in Windows shortcut files identified as “ZDI-CAN-25373.” This vulnerability allows attackers to conceal executed commands within specially crafted shortcut files. XDSpy has primarily targeted government entities in Eastern Europe and Russia since its activities became known in 2020. Researchers from HarfangLab found malicious LNK files exploiting this vulnerability in mid-March, revealing issues with how Windows parses LNK files. The infection begins with a ZIP archive containing a malicious LNK file, which triggers a complex Windows shell command to execute malicious components while displaying a decoy document. This command extracts and executes a first-stage malware called “ETDownloader,” which establishes persistence and downloads a second-stage payload known as “XDigo.” The XDigo implant, written in Go, collects sensitive information and employs encryption for data exfiltration. This campaign represents an evolution in XDSpy's tactics, combining zero-day exploitation with advanced multi-stage payloads.

Winsage

June 10, 2025

APT Hackers Exploited WebDAV 0-Day RCE Vulnerability in the Wild to Deploy Malware

A cyberattack campaign by the advanced persistent threat group Stealth Falcon targeted a prominent Turkish defense company using a zero-day vulnerability identified as CVE-2025-33053. This vulnerability allowed attackers to manipulate the working directory of legitimate Windows tools to execute malware from their WebDAV servers. The attack was initiated through a spear-phishing email containing a malicious .url file that directed the system to a legitimate Internet Explorer utility, which was then exploited to execute malicious files. The attackers employed process hollowing to bypass traditional defenses. Stealth Falcon, also known as FruityArmor, has been conducting cyber espionage since at least 2012, targeting government and defense sectors in Turkey, Qatar, Egypt, and Yemen. The attack involved a multi-stage infection chain leading to the deployment of "Horus Agent," a custom implant designed for advanced reconnaissance and equipped with anti-analysis techniques. Researchers identified additional custom tools used by Stealth Falcon, including a DC Credential Dumper and a custom keylogger. The group utilizes repurposed legitimate domains to blend their infrastructure with legitimate traffic, complicating detection efforts.

AppWizard

May 14, 2025

Marbled Dust leverages zero-day in Output Messenger for regional espionage

Since April 2024, the threat actor Marbled Dust has been exploiting a zero-day vulnerability (CVE-2025-27920) in the Output Messenger chat application, targeting user accounts that have not applied necessary fixes. This exploitation has resulted in the collection of sensitive data from users in Iraq, specifically linked to the Kurdish military. Microsoft has high confidence in this assessment and notes that Marbled Dust conducts reconnaissance to identify potential targets using Output Messenger. Marbled Dust has successfully utilized this vulnerability to deploy malicious files and exfiltrate data. Microsoft notified the application’s developer, Srimax, about the vulnerability, leading to the release of a software update. A second vulnerability (CVE-2025-27921) was also found, but no exploitation of this second flaw has been observed. The zero-day vulnerability allows an authenticated user to upload malicious files to the server's startup directory. Marbled Dust has exploited this flaw to place a backdoor file, OMServerService.vbs, in the startup folder, enabling them to access communications and sensitive data indiscriminately. The attack chain begins with Marbled Dust gaining access to the Output Messenger Server Manager, likely through DNS hijacking or other credential interception techniques. Once inside, they exploit the vulnerability to drop malicious files, including a GoLang backdoor, which connects to a Marbled Dust command-and-control domain for data exfiltration. To mitigate this threat, Microsoft recommends updating to the latest version of Output Messenger, activating various security protections, and implementing rigorous vulnerability management strategies. Microsoft Defender XDR customers can identify potential threat activity through specific alerts related to Marbled Dust and utilize advanced hunting queries for detection. Indicators of compromise include traffic to the domain api.wordinfos[.]com, associated with Marbled Dust activities.

Winsage

April 17, 2025

Windows NTLM hash leak flaw exploited in phishing attacks on governments

A vulnerability in Windows, identified as CVE-2025-24054, is being actively exploited in phishing campaigns targeting government and private sectors. Initially addressed in Microsoft's March 2025 Patch Tuesday, it was not considered actively exploited at that time. Researchers from Check Point reported increased exploitation activities shortly after the patches were released, particularly between March 20 and 25, 2025. Some attacks were linked to the Russian state-sponsored group APT28, but definitive attribution is lacking. The vulnerability allows attackers to capture NTLM hashes through phishing emails containing manipulated .library-ms files that trigger the flaw when interacted with. Check Point noted that subsequent attacks involved .library-ms files sent directly, requiring minimal user interaction to exploit. The malicious files also included additional components that exploit older vulnerabilities related to NTLM hash leaks. The attacker-controlled SMB servers were traced to specific IP addresses. Although rated as medium severity, the potential for authentication bypass and privilege escalation makes it a significant concern, prompting recommendations for organizations to install updates and disable NTLM authentication if not necessary.

Winsage

April 17, 2025

Hackers Exploiting NTLM Spoofing Vulnerability in Wild to Compromise Systems

Cybercriminals are exploiting a vulnerability in Windows systems known as CVE-2025-24054, which involves NTLM hash disclosure through spoofing techniques. This flaw allows attackers to leak NTLM hashes, leading to privilege escalation and lateral movement within networks. It is triggered when a user extracts a ZIP archive containing a malicious .library-ms file, causing Windows Explorer to initiate SMB authentication requests that expose NTLMv2-SSP hashes. Exploitation of this vulnerability began shortly after a security patch was released on March 11, 2025, with campaigns targeting government and private institutions in Poland and Romania. These campaigns utilized spear-phishing emails containing malicious ZIP archives, which, when interacted with, leaked NTLM hashes. The malicious files included various types designed to initiate SMB connections to attacker-controlled servers, allowing for pass-the-hash attacks and privilege escalation. The stolen hashes were sent to servers in several countries, indicating potential links to state-sponsored groups. One campaign involved Dropbox links that exploited the vulnerability upon user interaction. Microsoft has recommended immediate patching, enhancing network defenses, user education, network segmentation, and regular security audits to mitigate risks associated with this vulnerability.

Winsage

April 17, 2025

Windows NTLM vulnerability exploited in multiple attack campaigns (CVE-2025-24054)

CVE-2025-24054 is a vulnerability that allows attackers to capture NTLMv2-SSP hashes from a victim's machine during authentication requests to an attacker-controlled SMB server. Active exploitation of this vulnerability has been observed since March 19, 2025, targeting government and private sectors in Poland and Romania. The attacks involve phishing emails that lead victims to download an archive file containing exploits designed to leak NTLMv2-SSP hashes. Microsoft has released patches for this vulnerability, but users on older, unsupported versions may need to consider micropatching.

Winsage

March 28, 2025

Windows Users at Risk: New Zero-Day Exploit Steals Passwords Without Interaction

A newly uncovered zero-day vulnerability in Windows allows hackers to steal NTLM credentials simply by previewing a malicious file, affecting multiple Windows versions, including Windows 7 and Windows 11 v24H2. Microsoft has not yet issued a patch for this vulnerability, leaving millions of users exposed. The flaw was reported by security researcher Mitja Kolsek from ACROS Security, who noted that stolen credentials could lead to unauthorized access to networks. ACROS Security has created a temporary micro-patch available through its 0patch platform, which users are encouraged to implement. Additionally, a separate zero-day vulnerability identified in Google Chrome and other Chromium-based browsers allows attackers to bypass sandbox protection with a click on a malicious link, primarily targeting media organizations and government agencies in Russia. Users are advised to install the 0patch fix, avoid interacting with unfamiliar files, and update their browsers to protect against these threats.