{ "id": "ba91b977-7c81-4843-a801-741b7b9674e3", "created_at": "2026-04-06T00:07:00.147503Z", "updated_at": "2026-04-10T03:21:47.440617Z", "deleted_at": null, "sha1_hash": "933d6016f12dc648deabca7e54f17fd26aca1619", "title": "QR codes on Twitter deliver malicious Chrome extension", "llm_title": "", "authors": "", "file_creation_date": "0001-01-01T00:00:00Z", "file_modification_date": "0001-01-01T00:00:00Z", "file_size": 100664, "plain_text": "QR codes on Twitter deliver malicious Chrome extension\r\nBy Karsten Hahn\r\nPublished: 2022-02-04 · Archived: 2026-04-05 18:02:14 UTC\r\n02/03/2022\r\nReading time: 3 min (816 words)\r\nISO file downloads are advertised via QR codes on Twitter and on supposedly free gaming sites, but they don't\r\ncontain what they promise.\r\nQR codes on Twitter and malvertising\r\nThe loader for the malicious Chrome extension was initially analysed by @x3ph1 who dubbed it ChromeLoader.\r\nTo avoid misunderstandings with legitimate Chrome components we hereby refer to it as Choziosi loader. The\r\nanalysis on the loader is detailed but x3ph1 does not describe the Chrome extension Choziosi, which got me\r\nintrigued.\r\nTwitter user @th3_protoCOL found QR codes that circulate on Twitter and advertise pirated software to lure\r\npeople into downloading an ISO. Reddit users also complain about malicious ISO files on websites that provide\r\nSteam games. This tweet by @StopMalvertisin says the ISOs are downloaded via malicious advertisments.\r\nThe ISO file[3] has two main components. The _meta.txt contains a PowerShell script, which is encrypted with a\r\nsubstitution cipher. The downloader.exe[2] is a .NET assembly. It has a big dictionary with the substitution\r\nalphabet to decrypt the PowerShell script[4] in _meta.txt. It adds the PowerShell commands as scheduled task\r\nnamed ChromeTask which runs every ten minutes.\r\nOther variants of the same malware use dictionaries to combine words into a task name. The downloader.exe also\r\nshows an error message to the user, claiming that the operating system is incompatible with the program.\r\nhttps://www.gdatasoftware.com/blog/2022/01/37236-qr-codes-on-twitter-deliver-malicious-chrome-extension\r\nPage 1 of 4\n\ndownloader.exe schedules a task named ChromeTask which executes PowerShell\r\nThe PowerShell script downloads the Chrome extension archive.zip[1] from a malware server and installs it. Due\r\nto the scheduled task this continues to happen every ten minutes. This explains why some Reddit users complain\r\nthat Chrome closes itself all the time. This is a mishap of the malware developer because the annoyance factor will\r\nmake it more likely that affected users clean their system as soon as possible.\r\nMalicious Chrome extension\r\nThe Chrome extension itself has not been analysed yet. Possibly because of its hefty obfuscation. While trying to\r\ndebug the extension within Chrome, I already noticed that the extension settings chrome://extensions are\r\nredirected to the general settings chrome://settings. This prevents users from uninstalling the extension within\r\nChrome.\r\nThe extension consists of four files. The application icon is called properties.png and shows a gearwheel. The\r\nmanifest.json is part of every Chrome extension and has some metadata, e.g., about the icon location, extension\r\nname and permissions. The config.js contains the name of the extension, version number, C2 server and some\r\nform of id named _dd which is always sent as parameter to the server.\r\nThe main script is the background.js. It features control flow obfuscation via switch-case statement hopping\r\nwhich cannot be deobfuscated automatically by currently available tools. JavaScript Deobfuscator is able to\r\nperform intial cleanup, but the code remains unreadable. After identifying v0MM.T7 and v0MM.o7 as the ancor\r\npoints for function string decoding, I replaced the calls to these functions with their return value. A second pass to\r\nJavaScript Deobfuscator and manual cleanup of now unneeded functions leads to the final deobfuscated code[5].\r\nThe extension's main functionality is to serve advertisments and hijack search requests to Google, Yahoo and\r\nBing. Every three hours analytics are sent to the C2. The extension requests advertisments from the C2 server\r\nevery 30 minutes.\r\nhttps://www.gdatasoftware.com/blog/2022/01/37236-qr-codes-on-twitter-deliver-malicious-chrome-extension\r\nPage 2 of 4\n\nThe following image shows the extension's request to the C2 server in the first line and the server response in the\r\nsecond. The server provided a direct download link for a legitimate software product.\r\nfirst line: request to the server; second line: server response with a legitimate download link.\r\nConclusion\r\nWhen I started to work on this, I had admittedly other expectations on the malware's functionality. For now the\r\nonly purpose is getting revenue via unsolicited advertisments and search engine hijacking. But loaders often do\r\nnot stick to one payload in the long run and malware authors improve their projects over time. We will likely see\r\nmore of this threat in the future.\r\nFile hashes\r\nAll mentioned files, including the decoded and deobfuscated files, are available for download on MalwareBazaar.\r\nDescription SHA256\r\n[1] Chrome extension 6b1db4f891aa9033b615978a3fcfef02f1904f4eba984ba756ff5cd755d6f0b4\r\n[2] download.exe, .NET file 2d4454d610ae48bf9ffbb7bafcf80140a286898a7ffda39113da1820575a892f\r\n[3] ISO 8840f385340fad9dd452e243ad1a57fb44acfd6764d4bce98a936e14a7d0bfa6\r\n[4] Decrypted PowerShell\r\nscript\r\n2e958f481828ce7c59a3beab2ddac5561347e6f9bc25e6716c4524b845e83938\r\n[5] Deobfuscated\r\nbackground.js\r\n1c0254f0f811aadd6f1dad1cc5926f6b32fa2fb0866c35bf6a9f3dfad25fd9ca\r\nRelated articles:\r\nShare Article\r\n Content\r\nQR codes on Twitter and malvertising\r\nMalicious Chrome extension\r\nConclusion\r\nFile hashes\r\nRelated articles\r\nhttps://www.gdatasoftware.com/blog/2022/01/37236-qr-codes-on-twitter-deliver-malicious-chrome-extension\r\nPage 3 of 4\n\nSource: https://www.gdatasoftware.com/blog/2022/01/37236-qr-codes-on-twitter-deliver-malicious-chrome-extension\r\nhttps://www.gdatasoftware.com/blog/2022/01/37236-qr-codes-on-twitter-deliver-malicious-chrome-extension\r\nPage 4 of 4", "extraction_quality": 1, "language": "EN", "sources": [ "Malpedia" ], "references": [ "https://www.gdatasoftware.com/blog/2022/01/37236-qr-codes-on-twitter-deliver-malicious-chrome-extension" ], "report_names": [ "37236-qr-codes-on-twitter-deliver-malicious-chrome-extension" ], "threat_actors": [], "ts_created_at": 1775434020, "ts_updated_at": 1775791307, "ts_creation_date": 0, "ts_modification_date": 0, "files": { "pdf": "https://archive.orkl.eu/933d6016f12dc648deabca7e54f17fd26aca1619.pdf", "text": "https://archive.orkl.eu/933d6016f12dc648deabca7e54f17fd26aca1619.txt", "img": "https://archive.orkl.eu/933d6016f12dc648deabca7e54f17fd26aca1619.jpg" } }