{
	"id": "9119cb32-88d6-4211-99ad-8d96c0a64703",
	"created_at": "2026-04-06T00:10:07.281358Z",
	"updated_at": "2026-04-10T03:20:32.780143Z",
	"deleted_at": null,
	"sha1_hash": "da1bd8eeb39eb3f5d0982da9baf19b2e538405df",
	"title": "Malware vaccines can prevent pandemics, yet are rarely used",
	"llm_title": "",
	"authors": "",
	"file_creation_date": "0001-01-01T00:00:00Z",
	"file_modification_date": "0001-01-01T00:00:00Z",
	"file_size": 251826,
	"plain_text": "Malware vaccines can prevent pandemics, yet are rarely used\r\nBy Karsten Hahn\r\nPublished: 2022-01-19 · Archived: 2026-04-05 16:57:10 UTC\r\n01/19/2022\r\nReading time: 4 min (1118 words)\r\nVaccines have distinct advantages over detection based defense mechanisms, so we developed a vaccine to protect\r\nfrom one of the most notorious ransomware families—STOP/DJVU. But unlike vaccines against biological\r\nviruses, malware vaccines are not particularly common. This article explains why.\r\nInner workings of malware vaccines\r\nMalware vaccines apply harmless parts of malware to a system to trick malware into malfunction. It is not a\r\ncoincidence that the security industry adopted the term vaccine from medicine because there is a resemblence to\r\nmedical vaccines which apply inactive or weakened parts of viruses to a person in oder to protect. But the analogy\r\nstops there. Malware vaccines do not improve the security reponse of the system.\r\nThe harmless malware parts that vaccines apply are often so called infection markers. Malware usually tries not to\r\ninfect a system twice because this has unintended consequences. For that reason malware may place infection\r\nmarkers after a successful infection. If the malware finds such a marker, it will refrain from installing itself again.\r\nA vaccine just places those infection markers without the malware, thus tricking the malware into thinking it\r\nalready infected the system (cf. p. 2 [wich12]).\r\nVaccines can use other things than infection markers, e.g., they may cause an error in the malware by providing\r\ninvalid data. Some malware writes data into the registry or into files like encryption keys, configuration settings,\r\nC2C servers. A vaccine may place invalid data that causes the malware to crash, malfunction or simply not\r\nworking as intended by the author. A simple example would be the application of a non-existing C2C server for\r\nremotely controlled malware. One well-described vaccine that crashed previous versions of Emotet with a buffer\r\noverflow is called EmoCrash [quinn20].\r\nIn case of the STOP/DJVU ransomware vaccine, the ransomware is tricked into not encrypting files anymore.\r\nWithout file encryption there is no leverage to demand a ransom, thus, the main malicious behavior is disabled by\r\nthe vaccine.\r\nAnother, albeit different case, is the Logout4Shell vaccine by Cybereason. This vaccine is a benign malware akin\r\ntoWelchia worm. Benign malware has malware characteristics like worm-propagation or virus replication, or\r\nexploitation, but the payload is meant to fix a problem. Welchia worm got famous for using the same propagation\r\nmechanisms like Blaster worm to clean Blaster infections as well as patching vulnerable systems. Logout4Shell is\r\nhttps://www.gdatasoftware.com/blog/2022/01/malware-vaccines\r\nPage 1 of 4\n\nsimilar to Welchia because it actively exploits the Log4Shell vulnerability in order to fix the security hole. The\r\nexploitation itself is problematic because the changes can be applied without consent of the system's owner.\r\nCybereason states in a Bleepingcomputer article that the benefits outweigh the ethical concerns considering the\r\nseverety of Log4Shell exploit.\r\nAdvantages of vaccines over detection mechanisms\r\nMalware vaccines have some traits in common with those administered to combat biological\r\ninfections.\r\nVaccines have some unique advantages. They are passive, thus, unlike antivirus scanning they have no\r\nperformance overhead for the system. Depending on the malware they may also work on already infected systems\r\nby shutting down the malicious behavior of the dormant infection (p.3 [wich12]). Vaccines also work\r\nindependently from obfuscation, packing, polymorphism, metamorphism or similar evasion techniques.\r\nIn a study from 2012 at least 59.4% of the malware samples used infection markers (p.4 [wich12]). This study is\r\nobviously outdated, but the only one I could find about infection marker prevalence. I do believe that the\r\nmagnitude did not change and vaccines could be developed for a substantial amount of malware families.\r\nMalware vaccines are actively developed by some security companies, e.g., Minerva, however, compared to other\r\nmalware protection mechanism like signature based detection vaccinations seem rather unpopular. Why?\r\nTo understand this let's take a look at a specific vaccine first: The STOP/DJVU ransomware vaccine.\r\nSTOP/DJVU ransomware vaccine\r\nhttps://www.gdatasoftware.com/blog/2022/01/malware-vaccines\r\nPage 2 of 4\n\nSTOP/DJVU ransomware vaccine was created by John Parol and me. We published a tool on Github so that\r\neveryone can inspect and use it. Soon after publishing it, the tool got many false positive detections by antivirus\r\nvendors.\r\nAdditionally we added a section to our tool's readme to explain that systems are not entirely protected from\r\nSTOP/DJVU ransomware after using this vaccine. The ransomware will still do things to the system that are not\r\ntied to encryption.\r\nin some cases the ransomware may still create ransom notes\r\nif files are smaller than 6 bytes, the ransomware will still rename them, but not change their contents\r\nthis ransomware is often not alone but ships with additional malware like Vidar stealer, so disinfection of\r\nthe affected system is still necessary despite the vaccine\r\nSo the only thing that the vaccine prevents is the encryption and (for most files) renaming. It is not sure that the\r\nvaccine stays on the system because security products will likely remove it. STOP/DJVU ransomware itself may\r\nalso get an update at some point so that the vaccine does not work anymore.\r\nVaccines are no silver bullet\r\nThe main problem of vaccines is that they make a system look infected to other security products. Many of the\r\nmore tech-savvy users use malware scanners additionally to their main antivirus product and these scanners detect\r\ninfection markers as a sign of a prevalent infection. Not only do they remove these infection markers, they will\r\nfind them repeatedly when the antivirus product re-applies them. That turns using the products alongside each\r\nother into an unpleasant experience for the user, who may come to believe that their main antivirus does not work\r\nagainst this threat, and that their system is never properly cleaned.\r\nForcing malware scanners to not detect such infection markers is a bad idea because this would eventually weaken\r\ntheir detection against real threats. These markers are actual infection signs and should continue to be detected as\r\nhttps://www.gdatasoftware.com/blog/2022/01/malware-vaccines\r\nPage 3 of 4\n\nsuch. Hoping and preaching that users only use one security suite from one vendor is also not realistic. We have to\r\nlive with cross-usage of other scanners.\r\nAdditionally vaccine protection is oftentimes silent, which means users will never know that there was an\r\ninfection attempt. This is not desireable because users need to know that, e.g., the program they downloaded was a\r\nbad idea.\r\nMalware vaccines may stay a niche defense mechanism for the everyday malware, but they are specifically useful\r\nto combat pandemic outbreaks. In that regard they are not different to medical vaccines.\r\nShare Article\r\n Content\r\nInner workings of malware vaccines\r\nAdvantages of vaccines over detection mechanisms\r\nSTOP/DJVU ransomware vaccine\r\nVaccines are no silver bullet\r\nReferences\r\nSource: https://www.gdatasoftware.com/blog/2022/01/malware-vaccines\r\nhttps://www.gdatasoftware.com/blog/2022/01/malware-vaccines\r\nPage 4 of 4",
	"extraction_quality": 1,
	"language": "EN",
	"sources": [
		"Malpedia"
	],
	"references": [
		"https://www.gdatasoftware.com/blog/2022/01/malware-vaccines"
	],
	"report_names": [
		"malware-vaccines"
	],
	"threat_actors": [],
	"ts_created_at": 1775434207,
	"ts_updated_at": 1775791232,
	"ts_creation_date": 0,
	"ts_modification_date": 0,
	"files": {
		"pdf": "https://archive.orkl.eu/da1bd8eeb39eb3f5d0982da9baf19b2e538405df.pdf",
		"text": "https://archive.orkl.eu/da1bd8eeb39eb3f5d0982da9baf19b2e538405df.txt",
		"img": "https://archive.orkl.eu/da1bd8eeb39eb3f5d0982da9baf19b2e538405df.jpg"
	}
}