North Korean hackers have been exploiting a newly patched Windows zero-day vulnerability to take over victims’ systems, Check Point reports.
Attributed to the infamous Lazarus Group APT, the attacks represent a continuation of the long-running Operation Dream Job campaign targeting job seekers with fake work opportunities at well-known companies. North Korean hackers have been mounting fake job attack variations regularly.
Active since early 2026, the new campaign has been targeting the defense sector across multiple countries, mainly aerospace and aviation organizations in Europe and India, Check Point says.
Posing as recruiters, the attackers have contacted potential victims through popular professional platforms or direct messaging applications and convinced them to download a malicious payload.
As part of one infection chain, an archive containing a PDF viewer, a malicious DLL, and an encrypted payload posing as a PDF file is served to the victim, and DLL sideloading is used to execute the Mistpen malware downloader in memory while a decoy job description is shown on the screen.
The infection chain continues with reconnaissance, persistence, and the exploitation of a previously unknown vulnerability in Windows’ Ancillary Function Driver for WinSock (afd.sys), followed by the deployment of ForestTiger, a known Lazarus backdoor.
The afd.sys zero-day, now tracked as CVE-2026-68820, is a use-after-free issue that allows attackers to trigger a race condition and gain System privileges.
On August 11, Microsoft fixed the vulnerability as part of its Patch Tuesday updates, and the US cybersecurity agency CISA added it to its Known Exploited Vulnerabilities (KEV) catalog, urging federal agencies to patch it within the next two weeks.
According to Check Point, a second infection chain directs users to the trojanized PDF viewer SecurityPDF, which searches for a hidden marker in any PDF file opened on the system to execute the Troy backdoor directly in memory.
Troy is a new DLL implant that supports 17 operator commands, including file enumeration/download/upload, data exfiltration, shell access, process termination, and DLL injection.
The command-and-control (C&C) infrastructure observed in these attacks includes compromised Roundcube webmail deployments and CMS platforms, many vulnerable to CVE-2025-49113, a remote code execution (RCE) flaw that has been exploited since June 2025.
“These servers are infected with RelayShell, a previously undocumented PHP webshell that functions less like a conventional backdoor and more as a communication relay between infected endpoints and the operator, exchanging commands and responses through simple text files,” Check Point says.
The cybersecurity firm says that defense, aerospace, and aviation organizations in France, Germany, Brazil, and India have been targeted in the fresh campaign.
“Given the combination of a zero-day vulnerability that now has a patch, a new modular backdoor, and web-based infrastructure designed to resemble legitimate traffic, security teams in these sectors should prioritize the August Patch Tuesday update, review the indicators of compromise, and apply the same level of scrutiny to unsolicited recruiting outreach that they would apply to any unverified download request,” Check Point notes.
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