{
	"id": "dd1c7c28-0a5c-4ee7-bcfa-218b659a9d2f",
	"created_at": "2026-04-06T03:36:10.035955Z",
	"updated_at": "2026-04-10T03:20:38.045271Z",
	"deleted_at": null,
	"sha1_hash": "e85d9b52a5ab5e019da055e25f81690807161716",
	"title": "SamSam ransomware: controlled distribution for an elusive malware",
	"llm_title": "",
	"authors": "",
	"file_creation_date": "0001-01-01T00:00:00Z",
	"file_modification_date": "0001-01-01T00:00:00Z",
	"file_size": 1117720,
	"plain_text": "SamSam ransomware: controlled distribution for an elusive\r\nmalware\r\nBy Malwarebytes Labs\r\nPublished: 2018-06-18 · Archived: 2026-04-06 03:10:59 UTC\r\nSamSam ransomware has been involved in some high profile attacks recently, and remains a somewhat elusive\r\nmalware. In its time being active, SamSam has gone through a slight evolution, adding more features and\r\nalterations into the mix. These changes do not necessarily make the ransomware more dangerous, but they are\r\nadded to make it just a bit more tricky to detect or track as it is constantly changing.\r\nWhen comparing early samples to more recent samples, one thing remains constant: the ransomware payload (the\r\ncode that actually does disk encryption) is run-time decrypted. This is the most distinguishing trait about this\r\nransomware, the single feature that makes it unique. This encrypted payload scheme explains why it is extremely\r\ndifficult to find a sample of the actual payload code.\r\nThe main differences between the new and old versions of SamSam (which we will cover moving forward) are\r\nsimply:\r\n1. The modules used\r\n2. Their interactions with one another\r\nRather than covering the old version and then talking about the new one, we will go through the newer SamSam\r\ncode, and draw some comparisons to the older versions so we can understand its evolution.\r\nRecent SamSam analysis\r\nSamSam’s attacks have five main components to it in order for the compromise to take place. Four of them are\r\nactual files, and the fifth is the direct human involvement aspect.\r\nhttps://blog.malwarebytes.com/threat-analysis/2018/06/samsam-ransomware-controlled-distribution/\r\nPage 1 of 6\n\nComponent one is a batch file that contains some settings for the ransomware and is the only portion that the actor\r\nis actually executing manually. It runs a .NET exe, which eventually decrypts an encrypted stub file. The attacker\r\nexecutes the bat file on the compromised computer with a password as its command-line parameter. This is the\r\npassword that gets passed down the chain until the .NET file uses it for decryption. On older versions, it seems\r\nthat this bat file was not in the chain. The attacker possibly executed the .NET component directly.\r\nDetails on each portion below:\r\nIn this case, mswinupdate is the “runner,” as they call it here.  Basically, the “runner” is the loader file. It is a .NET\r\nexe that looks in the current folder for the ransomware payload to decrypt.\r\nNext, you see the SET password line, which receives the password via command-line parameter as we spoke\r\nabout above.\r\nThis is the whole reason there is so much difficulty in getting an analysis on the main payload. This password is\r\nentered without the use of a file. We may have trouble reconstructing the full manual attack scenario because some\r\nhttps://blog.malwarebytes.com/threat-analysis/2018/06/samsam-ransomware-controlled-distribution/\r\nPage 2 of 6\n\nfiles and logs are wiped afterward by the attacker. Because of this, the only way we can theoretically get the\r\npassword is if it’s intercepted at the time of the attack.\r\nMoving forward to the rest of the contents of the bat file, the remaining parameters are self-explanatory. The next\r\nline of interest executes the “runner” and then deletes itself, the runner, and the encryption DLL.\r\nAbove is component two, the “runner,” aka the payload decryptor and launcher. This file is not obfuscated and is\r\nquite simple in functionality. It searches directories for a file with an extension of .stubbin that will have been\r\nplaced there by the attacker. The stubbin file is the encrypted ransomware. It immediately reads the bytes from the\r\nfile and then deletes the file from the disk. The contents of the file are AES encrypted so even having the stubbin\r\nfile does not help us in analysis unless we obtain the password manually entered by the attacker.\r\nThe stubbin file calls the assembly.Load function, which loads up a .NET file dynamically. The function receives a\r\nparameter, which is the output of the decryptor method. This means that it decrypts the stub file, turning it into a\r\nproper PE, and then loads it dynamically. The password turned in from the bat file is args[0], while Arg_4E_0 is\r\nthe encrypted byte stream. It then initiates the decrypted file for execution.\r\nOn to component three. In the recent versions of SamSam, the decryption code is contained in a separate DLL,\r\nwhile in the older versions, it was all contained within the runner EXE. The older versions therefore had only\r\nthree components, rather than four.\r\nHere is a screenshot of the decryption code:\r\nhttps://blog.malwarebytes.com/threat-analysis/2018/06/samsam-ransomware-controlled-distribution/\r\nPage 3 of 6\n\nThroughout the program code you will see the following:\r\nThis is something that was also added in the recent version. These arrays are unused, perhaps just garbage code\r\ninserted for obfuscation or to throw off signatures.\r\nhttps://blog.malwarebytes.com/threat-analysis/2018/06/samsam-ransomware-controlled-distribution/\r\nPage 4 of 6\n\nAnd finally, component four, the contents of the encrypted malware payload, *.stubbin\r\nThe goal of SamSam: targeted attacks\r\nIn this analysis, we spoke a lot about the password and the fact that it was entered manually by the\r\nattacker. This is the most important point about this ransomware campaign. As analysts, without\r\nknowing the password, we cannot analyze the ransomware code. But what is more important to note\r\nis that we cannot even execute the ransomware on a victim or test machine. This means that only\r\nthe author, (or someone who has intercepted the author’s password) can run this attack.\r\nThis is a major difference from the vast majority of ransomware, or even malware, out there. SamSam is not the\r\ntype of ransomware that spreads like wildfire. In fact, this ransomware quite literally cannot spread automatically\r\nand naturally.\r\nA victim who accidentally downloads and executes this malware will not be harmed at all because a password is\r\nrequired for the payload to run.  It requires the human involvement of the creator, which means it was developed\r\nfor a single purpose: targeted attacks. The author attacks victims he has specifically chosen. And this is what\r\nmakes this ransomware so interesting. The author is not just after a quick buck; instead, he prefers to have his\r\npayload remain a secret so he can continue to take down only the people he chooses.\r\nNotes\r\nResearchers Dorka Palotay and Peter Mackenzie from Sophos Labs also covered SamSam in a recent paper, to\r\nsee their take, check it out here.\r\nIndicators of compromise\r\nBAT file\r\n9C8AD4147F5CBDDA51317A857D75720C84BDDB16338DABE374A3E60C64C2F0DE\r\nEncryption DLL\r\nDA9C2ECC88E092E3B8C13C6D1A71B968AA6F705EB5966370F21E306C26CD4FB5\r\nhttps://blog.malwarebytes.com/threat-analysis/2018/06/samsam-ransomware-controlled-distribution/\r\nPage 5 of 6\n\nRunner\r\n738C95F5BFE63A530B200A0D73F363D46C5671C1FCBB69C217E15A3516501A86\r\nStubbin\r\n594B9B42A2D7AE71EF08795FCA19D027135D86E82BC0D354D18BFD766EC2424C\r\nSource: https://blog.malwarebytes.com/threat-analysis/2018/06/samsam-ransomware-controlled-distribution/\r\nhttps://blog.malwarebytes.com/threat-analysis/2018/06/samsam-ransomware-controlled-distribution/\r\nPage 6 of 6",
	"extraction_quality": 1,
	"language": "EN",
	"sources": [
		"ETDA"
	],
	"references": [
		"https://blog.malwarebytes.com/threat-analysis/2018/06/samsam-ransomware-controlled-distribution/"
	],
	"report_names": [
		"samsam-ransomware-controlled-distribution"
	],
	"threat_actors": [],
	"ts_created_at": 1775446570,
	"ts_updated_at": 1775791238,
	"ts_creation_date": 0,
	"ts_modification_date": 0,
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