{ "id": "e8482d67-e1ec-4630-a62e-c26695093456", "created_at": "2026-04-06T00:06:50.421461Z", "updated_at": "2026-04-10T03:24:29.208655Z", "deleted_at": null, "sha1_hash": "ff57bd0dcb8a2292de91e0f0c5a0fc4b0d5a25f2", "title": "BKDR_URSNIF.SM - Threat Encyclopedia | Trend Micro (US)", "llm_title": "", "authors": "", "file_creation_date": "0001-01-01T00:00:00Z", "file_modification_date": "0001-01-01T00:00:00Z", "file_size": 82576, "plain_text": "BKDR_URSNIF.SM - Threat Encyclopedia | Trend Micro (US)\r\nBy Analysis by: Sabrina Lei Sioting\r\nArchived: 2026-04-05 21:28:43 UTC\r\nThis backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by\r\nusers when visiting malicious sites.\r\nIt executes commands from a remote malicious user, effectively compromising the affected system.\r\nArrival Details\r\nThis backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by\r\nusers when visiting malicious sites.\r\nInstallation\r\nThis backdoor drops the following copies of itself into the affected system:\r\n%User Profile%\\nah_{4 random characters}.exe\r\n(Note: %User Profile% is the current user's profile folder, which is usually C:\\Documents and Settings\\{user\r\nname} on Windows 2000, XP, and Server 2003, or C:\\Users\\{user name} on Windows Vista and 7.)\r\nIt adds the following mutexes to ensure that only one of its copies runs at any one time:\r\nxmas_mutex\r\nAutostart Technique\r\nThis backdoor adds the following registry entries to enable its automatic execution at every system startup:\r\nHKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\\r\nWindows\\CurrentVersion\\Run\r\nnah_Shell = \"%User Profile%\\nah_{4 random characters}.exe\"\r\nOther System Modifications\r\nThis backdoor adds the following registry entries as part of its installation routine:\r\nHKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\\r\nWindows\\CurrentVersion\r\nnah_opt_reserv = \"{BLOCKED}13.106 \"\r\nHKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\\r\nWindows\\CurrentVersion\r\nhttps://www.trendmicro.com/vinfo/us/threat-encyclopedia/malware/BKDR_URSNIF.SM?_ga=2.129468940.1462021705.1559742358-1202584019.1549394279\r\nPage 1 of 7\n\nnah_opt_forms = \"/system/prinimalka.py/forms\"\r\nHKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\\r\nWindows\\CurrentVersion\r\nnah_opt_options = \"/system/prinimalka.py/options\"\r\nHKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\\r\nWindows\\CurrentVersion\r\nnah_opt_command = \"/system/prinimalka.py/command\"\r\nHKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\\r\nWindows\\CurrentVersion\r\nnah_opt_file = \"/system/prinimalka.py/cookies\"\r\nHKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\\r\nWindows\\CurrentVersion\r\nnah_opt_ss = \"/cgi-bin/trash.py\"\r\nHKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\\r\nWindows\\CurrentVersion\r\nnah_opt_pstorage = \"/cgi-bin/trash.py\"\r\nHKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\\r\nWindows\\CurrentVersion\r\nnah_opt_certs = \"/cgi-bin/trash.py\"\r\nHKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\\r\nWindows\\CurrentVersion\r\nnah_opt_idproject = \"000055\"\r\nHKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\\r\nWindows\\CurrentVersion\"\r\nnah_opt_pauseopt = \"1200\"\r\nBackdoor Routine\r\nThis backdoor executes the following commands from a remote malicious user:\r\nArchive and upload file(s)\r\nCapture screenshot\r\nClear cookies\r\nDownload and Execute other files\r\nList running process\r\nReboot the affected system\r\nSteal certificates and cookies\r\nUpdate/Download a configuration file\r\nhttps://www.trendmicro.com/vinfo/us/threat-encyclopedia/malware/BKDR_URSNIF.SM?_ga=2.129468940.1462021705.1559742358-1202584019.1549394279\r\nPage 2 of 7\n\nUpload a log file which contains stolen information\r\nIt connects to the following URL(s) to send and receive commands from a remote malicious user:\r\nhttp://{BLOCKED}3.2/system/prinimalka.py/command\r\nStolen Information\r\nThis backdoor sends the gathered information via HTTP POST to the following URL:\r\nhttp://{BLOCKED}3.2/system/prinimalka.py/forms\r\nNOTES:\r\nIt checks the existence of the following registry key:\r\nHKEY_CURRENT_USER\\Software\\Classes\\FirefoxHTML\\shell\\open\\command\r\nIf it exists, it gets the folder location of firefox.exe and creates the following file:\r\n{folder location}\\chrome\\amba.jar\r\nOncethe file mentioned above is executed, it drops the following file:\r\n{folder location}\\chrome\\amba.js - detected as JS_URSNIF.DJ\r\nIt also modifies the following file to point to amba.jar:\r\n{folder path}\\chrome\\browser.manifest\r\nIt injects itself into all running processes to remain memory-resident except for the following processes:\r\nsvchost.exe\r\n[System Process]\r\nSystem\r\nsmss.exe\r\nwinlogon.exe\r\nlsass.exe\r\navp\r\ncsrss.exe\r\nservices.exe\r\nIt hooks the following API calls to hide its behavior on the affected system:\r\nCreateProcessA\r\nCreateProcessW\r\nFindFirstFileA\r\nFindNextFileA\r\nFindFirstFileW\r\nhttps://www.trendmicro.com/vinfo/us/threat-encyclopedia/malware/BKDR_URSNIF.SM?_ga=2.129468940.1462021705.1559742358-1202584019.1549394279\r\nPage 3 of 7\n\nFindNextFileW\r\nRegEnumValueA\r\nRegEnumValueW\r\nIt hooks the following API calls to search for network traffic for a predetermined HTML elements:\r\nInternetCloseHandle\r\nInternetQueryDataAvailable\r\nInternetReadFile\r\nInternetReadFileExA\r\nHttpSendRequestA\r\nHttpSendRequestW\r\nHttpOpenRequestW\r\nHttpOpenRequestAl\r\nIt attempts to steal sensitive online banking information, such as user names and passwords from the following\r\nfinancial institutions:\r\ntrade\r\nschwab\r\nfidelity\r\npaypal\r\nwamu bank\r\nwellsfargo\r\nsuntrust\r\nusaa\r\nwachovia\r\nIt does this by injecting certain HTML codes to the site.\r\nStep 2\r\nRemove the malware/grayware file dropped/downloaded by BKDR_URSNIF.SM\r\n JS_URSNIF.DJ\r\nStep 3\r\nSince this malware cannot be removed in normal and safe mode, it is necessary to restart using the Windows\r\nRecovery Console. To restart the system using the Windows Recovery Console:\r\n• On Windows XP and Server 2003 systems:\r\n1. Click Start\u003eRun. In the Open input box, type secpol.msc and press Enter.\r\n2. In the left panel, double-click Local Policies\u003eSecurity Options.\r\n3. In the right panel, double-click Recovery Console: Allow floppy copy and access to all drives and folders.\r\n4. Select Enabled and click OK.\r\nhttps://www.trendmicro.com/vinfo/us/threat-encyclopedia/malware/BKDR_URSNIF.SM?_ga=2.129468940.1462021705.1559742358-1202584019.1549394279\r\nPage 4 of 7\n\n5. Insert the Windows Installation CD into the CD drive, then restart your computer.\r\n6. When prompted, press any key to boot from the CD.\r\n7. On the main menu, type r to go to the Recovery Console.\r\n8. Type the number that corresponds to the drive and directory that contains Windows (usually\r\nC:\\WINDOWS) and press Enter.\r\n9. Type the Administrator password and press Enter.\r\n10. In the input box, type the following then press Enter:\r\nSET AllowAllPaths = TRUE\r\ndel %User Profile%\\nah_{4 random characters}.exe\r\n11. Type exit and press Enter to restart the system normally.\r\n• On Windows Vista and 7 systems:\r\n1. Insert your Windows Installation DVD in the DVD drive, then Press the restart button.\r\n2. When prompted, press any key to boot from the DVD.\r\n3. Depending on your Windows Installation DVD, you might be required to select the installation language.\r\nThen on the Install Windows window, choose your language, locale, and keyboard layout or input method.\r\nClick Next, then click Repair your computer.\r\n4. Select Use recovery tools that can help fix problems starting Windows. Select your installation of\r\nWindows. Click Next.\r\n5. If the Startup Repair window appears, click Cancel, Yes, then Finish.\r\n6. In the System Recovery Options window, click Command Prompt.\r\n7. In the Command Prompt window, type the following then press Enter:\r\ndel %User Profile%\\nah_{4 random characters}.exe\r\n(Note: In Windows 7, all local drives will be assigned one more than normal. For example, the C: drive\r\nbecomes D:.)\r\n8. Type exit and press Enter to close the Command Prompt window.\r\n9. Click Restart to restart the system normally.\r\nStep 4\r\nDelete this registry value\r\n[ Learn More ]\r\nImportant: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this\r\nstep only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft\r\narticleopen on a new tab first before modifying your computer's registry.\r\nIn HKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Run\r\nnah_Shell = \"%User Profile%\\nah_{4 random characters}.exe\"\r\nIn HKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\r\nnah_opt_reserv = \"{BLOCKED}13.106\"\r\nIn HKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\r\nnah_opt_forms = \"/system/prinimalka.py/forms\"\r\nhttps://www.trendmicro.com/vinfo/us/threat-encyclopedia/malware/BKDR_URSNIF.SM?_ga=2.129468940.1462021705.1559742358-1202584019.1549394279\r\nPage 5 of 7\n\nIn HKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\r\nnah_opt_options = \"/system/prinimalka.py/options\"\r\nIn HKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\r\nnah_opt_command = \"/system/prinimalka.py/command\"\r\nIn HKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\r\nnah_opt_file = \"/system/prinimalka.py/cookies\"\r\nIn HKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\r\nnah_opt_ss = \"/cgi-bin/trash.py\"\r\nIn HKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\r\nnah_opt_pstorage = \"/cgi-bin/trash.py\"\r\nIn HKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\r\nnah_opt_certs = \"/cgi-bin/trash.py\"\r\nIn HKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\r\nnah_opt_idproject = \"000055\"\r\nIn HKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\"\r\nnah_opt_pauseopt = \"1200\"\r\nStep 5\r\nSearch and delete this file\r\n[ Learn More ]\r\nThere may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders\r\ncheckbox in the \"More advanced options\" option to include all hidden files and folders in the search result. {folder\r\nlocation}\\chrome\\amba.jar\r\nStep 6\r\nScan your computer with your Trend Micro product to delete files detected as BKDR_URSNIF.SM. If the\r\ndetected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is\r\nrequired. You may opt to simply delete the quarantined files. Please check this Knowledge Base pageopen on a\r\nnew tab for more information.\r\nStep 7\r\nRestore deleted/modified files and/or registry entries from backup\r\n*Note: Only Microsoft-related files/keys/values will be restored. If this malware/grayware also deleted registry\r\nkeys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.\r\n{folder path}\\chrome\\browser.manifest\r\nDid this description help? Tell us how we did.open on a new tab\r\nhttps://www.trendmicro.com/vinfo/us/threat-encyclopedia/malware/BKDR_URSNIF.SM?_ga=2.129468940.1462021705.1559742358-1202584019.1549394279\r\nPage 6 of 7\n\nSource: https://www.trendmicro.com/vinfo/us/threat-encyclopedia/malware/BKDR_URSNIF.SM?_ga=2.129468940.1462021705.1559742358\r\n-1202584019.1549394279\r\nhttps://www.trendmicro.com/vinfo/us/threat-encyclopedia/malware/BKDR_URSNIF.SM?_ga=2.129468940.1462021705.1559742358-1202584019.1549394279\r\nPage 7 of 7", "extraction_quality": 1, "language": "EN", "sources": [ "MITRE" ], "references": [ "https://www.trendmicro.com/vinfo/us/threat-encyclopedia/malware/BKDR_URSNIF.SM?_ga=2.129468940.1462021705.1559742358-1202584019.1549394279" ], "report_names": [ "BKDR_URSNIF.SM?_ga=2.129468940.1462021705.1559742358-1202584019.1549394279" ], "threat_actors": [ { "id": "aa73cd6a-868c-4ae4-a5b2-7cb2c5ad1e9d", "created_at": "2022-10-25T16:07:24.139848Z", "updated_at": "2026-04-10T02:00:04.878798Z", "deleted_at": null, "main_name": "Safe", "aliases": [], "source_name": "ETDA:Safe", "tools": [ "DebugView", "LZ77", "OpenDoc", "SafeDisk", "TypeConfig", "UPXShell", "UsbDoc", "UsbExe" ], "source_id": "ETDA", "reports": null } ], "ts_created_at": 1775434010, "ts_updated_at": 1775791469, "ts_creation_date": 0, "ts_modification_date": 0, "files": { "pdf": "https://archive.orkl.eu/ff57bd0dcb8a2292de91e0f0c5a0fc4b0d5a25f2.pdf", "text": "https://archive.orkl.eu/ff57bd0dcb8a2292de91e0f0c5a0fc4b0d5a25f2.txt", "img": "https://archive.orkl.eu/ff57bd0dcb8a2292de91e0f0c5a0fc4b0d5a25f2.jpg" } }