{ "id": "834078c6-5a0d-498f-8db5-0bb4e97e6353", "created_at": "2026-04-06T00:11:46.930648Z", "updated_at": "2026-04-10T03:32:43.714724Z", "deleted_at": null, "sha1_hash": "296cef5c8859253e4d7d8fa2e3bcd3888a37ee45", "title": "Hackers abuse Windows error reporting tool to deploy malware", "llm_title": "", "authors": "", "file_creation_date": "0001-01-01T00:00:00Z", "file_modification_date": "0001-01-01T00:00:00Z", "file_size": 3525897, "plain_text": "Hackers abuse Windows error reporting tool to deploy malware\r\nBy Bill Toulas\r\nPublished: 2023-01-04 · Archived: 2026-04-05 20:31:23 UTC\r\nHackers are abusing the Windows Problem Reporting (WerFault.exe) error reporting tool for Windows to load malware into\r\na compromised system's memory using a DLL sideloading technique.\r\nThe use of this Windows executable is to stealthy infect devices without raising any alarms on the breached system by\r\nlaunching the malware through a legitimate Windows executable.\r\nThe new campaign was spotted by K7 Security Labs, which could not identify the hackers, but they are believed to be based\r\nin China.\r\nhttps://www.bleepingcomputer.com/news/security/hackers-abuse-windows-error-reporting-tool-to-deploy-malware/\r\nPage 1 of 5\n\n0:00\r\nhttps://www.bleepingcomputer.com/news/security/hackers-abuse-windows-error-reporting-tool-to-deploy-malware/\r\nPage 2 of 5\n\nVisit Advertiser websiteGO TO PAGE\r\nAbusing WerFault.exe\r\nThe malware campaign starts with the arrival of an email with an ISO attachment. When double-clicked, the ISO will mount\r\nitself as a new drive letter containing a legitimate copy of the Windows WerFault.exe executable, a DLL file ('faultrep.dll'),\r\nan XLS file ('File.xls'), and a shortcut file ('inventory \u0026 our specialties.lnk').\r\nFiles contained in the ISO\r\nSource: K7 Labs\r\nThe victim starts the infection chain by clicking on the shortcut file, which uses 'scriptrunner.exe' to execute WerFault.exe.\r\nWerFault is the standard Windows error reporting tool used in Windows 10 and 11, allowing the system to track and report\r\nerrors related to the operating system or applications.\r\nWindows use the tool to report an error and receive potential solution recommendations.\r\nAntivirus tools commonly trust WerFault as it's a legitimate Windows executable signed by Microsoft, so launching it on the\r\nsystem won't usually trigger alerts to warn the victim.\r\nWhen WerFault.exe is launched, it will use a known DLL sideloading flaw to load the malicious 'faultrep.dll' DLL contained\r\nin the ISO.\r\nNormally, the 'faultrep.dll' file is a legitimate DLL by Microsoft in the C:\\Windows\\System folder required for WerFault to\r\nrun correctly. However, the malicious DLL version in the ISO contains additional code to launch the malware.\r\nThe technique of creating malicious DLLs under the same name as a legitimate one so that it is loaded instead is called DLL\r\nsideloading.\r\nDLL sideloading requires a malicious version of a DLL to be located in the same directory as the executable that invokes it.\r\nWhen the executable is launched, Windows will prioritize it over its native DLL as long as it has the same name.\r\nWhen the DLL is loaded in this attack, it will create two threads, one that loads Pupy Remote Access Trojan's DLL\r\n('dll_pupyx64.dll') into memory and one that opens the included XLS spreadsheet to serve as a decoy.\r\nhttps://www.bleepingcomputer.com/news/security/hackers-abuse-windows-error-reporting-tool-to-deploy-malware/\r\nPage 3 of 5\n\nComplete infection chain\r\nSource: K7 Labs\r\nPupy RAT is an open-source and publicly available malware written in Python that supports reflective DLL loading to evade\r\ndetection, and additional modules are downloaded later.\r\nThe malware allows threat actors to gain full access to the infected devices, enabling them to execute commands, steal data,\r\ninstall further malware, or spread laterally through a network.\r\nAs an open-source tool, it has been used by several state-backed espionage actors like the Iranian APT33 and APT35 groups,\r\nas those tools make attribution and persistent operation harder to track.\r\nQBot malware distributors were seen adopting a similar attack chain last summer, abusing the Windows Calculator to evade\r\ndetection by security software.\r\nhttps://www.bleepingcomputer.com/news/security/hackers-abuse-windows-error-reporting-tool-to-deploy-malware/\r\nPage 4 of 5\n\nAutomated Pentesting Covers Only 1 of 6 Surfaces.\r\nAutomated pentesting proves the path exists. BAS proves whether your controls stop it. Most teams run one without the\r\nother.\r\nThis whitepaper maps six validation surfaces, shows where coverage ends, and provides practitioners with three diagnostic\r\nquestions for any tool evaluation.\r\nSource: https://www.bleepingcomputer.com/news/security/hackers-abuse-windows-error-reporting-tool-to-deploy-malware/\r\nhttps://www.bleepingcomputer.com/news/security/hackers-abuse-windows-error-reporting-tool-to-deploy-malware/\r\nPage 5 of 5", "extraction_quality": 1, "language": "EN", "sources": [ "MITRE" ], "references": [ "https://www.bleepingcomputer.com/news/security/hackers-abuse-windows-error-reporting-tool-to-deploy-malware/" ], "report_names": [ "hackers-abuse-windows-error-reporting-tool-to-deploy-malware" ], "threat_actors": [ { "id": "a63c994f-d7d6-4850-a881-730635798b90", "created_at": "2025-08-07T02:03:24.788883Z", "updated_at": "2026-04-10T02:00:03.785146Z", "deleted_at": null, "main_name": "COBALT TRINITY", "aliases": [ "APT33 ", "Elfin ", "HOLMIUM ", "MAGNALIUM ", "Peach Sandstorm ", "Refined Kitten ", "TA451 " ], "source_name": "Secureworks:COBALT TRINITY", "tools": [ "AutoCore", "Cadlotcorg", "Dello RAT", "FalseFont", "Imminent Monitor", "KDALogger", "Koadic", "NanoCore", "NetWire", "POWERTON", "PoshC2", "Poylog", "PupyRAT", "Schoolbag" ], "source_id": "Secureworks", "reports": null }, { "id": "d8af157e-741b-4933-bb4a-b78490951d97", "created_at": "2023-01-06T13:46:38.748929Z", "updated_at": "2026-04-10T02:00:03.087356Z", "deleted_at": null, "main_name": "APT35", "aliases": [ "COBALT MIRAGE", "Agent Serpens", "Newscaster Team", "Magic Hound", "G0059", "Phosphorus", "Mint Sandstorm", "TunnelVision" ], "source_name": "MISPGALAXY:APT35", "tools": [], "source_id": "MISPGALAXY", "reports": null }, { "id": "e3676dfe-3d40-4b3a-bfbd-4fc1f8c896f4", "created_at": "2022-10-25T15:50:23.808974Z", "updated_at": "2026-04-10T02:00:05.291959Z", "deleted_at": null, "main_name": "Magic Hound", "aliases": [ "Magic Hound", "TA453", "COBALT ILLUSION", "Charming Kitten", "ITG18", "Phosphorus", "APT35", "Mint Sandstorm" ], "source_name": "MITRE:Magic Hound", "tools": [ "Impacket", "CharmPower", "FRP", "Mimikatz", "Systeminfo", "ipconfig", "netsh", "PowerLess", "Pupy", "DownPaper", "PsExec" ], "source_id": "MITRE", "reports": null }, { "id": "e5ff825b-0456-4013-b90a-971b93def74a", "created_at": "2022-10-25T15:50:23.824058Z", "updated_at": "2026-04-10T02:00:05.377261Z", "deleted_at": null, "main_name": "APT33", "aliases": [ "APT33", "HOLMIUM", "Elfin", "Peach Sandstorm" ], "source_name": "MITRE:APT33", "tools": [ "PowerSploit", "AutoIt backdoor", "PoshC2", "Mimikatz", "NanoCore", "DEADWOOD", "StoneDrill", "POWERTON", "LaZagne", "TURNEDUP", "NETWIRE", "Pupy", "ftp" ], "source_id": "MITRE", "reports": null }, { "id": "99c7aace-96b1-445b-87e7-d8bdd01d5e03", "created_at": "2025-08-07T02:03:24.746965Z", "updated_at": "2026-04-10T02:00:03.640335Z", "deleted_at": null, "main_name": "COBALT ILLUSION", "aliases": [ "APT35 ", "APT42 ", "Agent Serpens Palo Alto", "Charming Kitten ", "CharmingCypress ", "Educated Manticore Checkpoint", "ITG18 ", "Magic Hound ", "Mint Sandstorm sub-group ", "NewsBeef ", "Newscaster ", "PHOSPHORUS sub-group ", "TA453 ", "UNC788 ", "Yellow Garuda " ], "source_name": "Secureworks:COBALT ILLUSION", "tools": [ "Browser Exploitation Framework (BeEF)", "MagicHound Toolset", "PupyRAT" ], "source_id": "Secureworks", "reports": null }, { "id": "b23e717c-0b27-47e0-b3c8-4defe6dd857f", "created_at": "2023-01-06T13:46:38.367369Z", "updated_at": "2026-04-10T02:00:02.945356Z", "deleted_at": null, "main_name": "APT33", "aliases": [ "Elfin", "MAGNALLIUM", "HOLMIUM", "COBALT TRINITY", "G0064", "ATK35", "Peach Sandstorm", "TA451", "APT 33", "Refined Kitten" ], "source_name": "MISPGALAXY:APT33", "tools": [], "source_id": "MISPGALAXY", "reports": null } ], "ts_created_at": 1775434306, "ts_updated_at": 1775791963, "ts_creation_date": 0, "ts_modification_date": 0, "files": { "pdf": "https://archive.orkl.eu/296cef5c8859253e4d7d8fa2e3bcd3888a37ee45.pdf", "text": "https://archive.orkl.eu/296cef5c8859253e4d7d8fa2e3bcd3888a37ee45.txt", "img": "https://archive.orkl.eu/296cef5c8859253e4d7d8fa2e3bcd3888a37ee45.jpg" } }