{ "id": "88f99033-dae7-4d7c-9ba5-0d6dc8549952", "created_at": "2026-04-06T00:07:33.789378Z", "updated_at": "2026-04-10T03:29:06.274433Z", "deleted_at": null, "sha1_hash": "6d767cfdcb90be3ef47a2c754ddefd651bd8c184", "title": "BlackMatter: New Data Exfiltration Tool Used in Attacks", "llm_title": "", "authors": "", "file_creation_date": "0001-01-01T00:00:00Z", "file_modification_date": "0001-01-01T00:00:00Z", "file_size": 54838, "plain_text": "BlackMatter: New Data Exfiltration Tool Used in Attacks\r\nBy About the Author\r\nArchived: 2026-04-05 17:43:55 UTC\r\nAt least one affiliate of the BlackMatter ransomware operation has begun using a custom data exfiltration tool in\r\nits attacks. Exmatter, which was discovered by Symantec’s Threat Hunter Team, is designed to steal specific file\r\ntypes from a number of selected directories and upload them to an attacker-controlled server prior to deployment\r\nof the ransomware itself on the victim’s network.\r\nThis is the third time a custom data exfiltration tool appears to have been developed by ransomware operators,\r\nfollowing the earlier discovery of the Ryuk Stealer tool and StealBit, which is linked to the LockBit ransomware\r\noperation.\r\nExmatter in action\r\nExmatter is compiled as a .NET executable and obfuscated. When run, it checks its command line arguments for\r\nthe following strings: \"nownd\" and \"-nownd\". If either is found, it attempts to hide its own window by calling the\r\n\"ShowWindow\" API as follows:\r\nShowWindow(Process.GetCurrentProcess().MainWindowHandle, 0);\r\nIn order to identify files for exfiltration, it will retrieve the drive names of all logical drives on the infected\r\ncomputer and collect all file path names, disregarding anything under the following directories:\r\nC:\\Documents and Settings\r\nC:\\PerfLogs\r\nC:\\Program Files\\Windows Defender Advanced Threat Protection\\Classification\\Configuration\r\nC:\\Program Files\\WindowsApps\r\nC:\\ProgramData\\Application Data\r\nC:\\ProgramData\\Desktop\r\nC:\\ProgramData\\Documents\r\nC:\\ProgramData\\Microsoft\r\nC:\\ProgramData\\Packages\r\nC:\\ProgramData\\Start Menu\r\nC:\\ProgramData\\Templates\r\nC:\\ProgramData\\WindowsHolographicDevices\r\nC:\\Recovery\r\nC:\\System Volume Information\r\nC:\\Users\\All Users\r\nC:\\Users\\Default\r\nC:\\Users\\Public\\Documents\r\nhttps://symantec-enterprise-blogs.security.com/blogs/threat-intelligence/blackmatter-data-exfiltration\r\nPage 1 of 4\n\nC:\\Windows\r\nIt will also exclude files of less than 1,024 bytes in size and files with the following attributes:\r\nFileAttributes.System\r\nFileAttributes.Temporary\r\nFileAttributes.Directory\r\nIt will only exfiltrate files with the following extensions:\r\n.doc\r\n.docx\r\n.xls\r\n.xlsx\r\n.pdf\r\n.msg\r\n.png\r\n.ppt\r\n.pptx\r\n.sda\r\n.sdm\r\n.sdw\r\n.csv\r\nIt attempts to prioritize files for exfiltration by using LastWriteTime.\r\nFiles that match the criteria are then uploaded to a remote SFTP server using the following parameters:\r\nHost: 165.22.84.147\r\nPort: 22\r\nExmatter also includes SOCKS5 configuration, but this is not used:\r\nHost: 10.26.16.181\r\nPort: 1080\r\nWhen it has finished exfiltrating data, Exmatter starts the following process to remove any trace of itself:\r\nFilename: \"powershell.exe\"\r\nArguments:\r\n-WindowStyle Hidden -C $path = '[FILEPATH_OF_THE_EXECUTING_SAMPLE]';Get-Process |\r\nWhere-Object {$_.Path -like $path} | Stop-Process -Force;[byte[]]$arr = new-object byte[]\r\n65536;Set-Content -Path $path -Value $arr;Remove-Item -Path $path;\r\nThis will attempt to overwrite an initial chunk of the file before deleting it.\r\nNewer variants\r\nhttps://symantec-enterprise-blogs.security.com/blogs/threat-intelligence/blackmatter-data-exfiltration\r\nPage 2 of 4\n\nMultiple variants of Exmatter have been found, suggesting that the attackers have continued to refine the tool in\r\norder to expedite exfiltration of a sufficient volume of high value data in as short a time as possible.\r\nIn a second variant, the directory “C:\\Program Files\\Windows Defender Advanced Threat\r\nProtection\\Classification\\Configuration” has been replaced with “C:\\Program Files\\Windows Defender Advanced\r\nThreat Protection\" on the exclusion list. The file types “.xlsm”, and “.zip” were added to the inclusion list.\r\nA third version of note added a WebDav client. The code structure suggests that SFTP remains the first choice\r\nprotocol, with WebDav acting as a backup. The WebDav client uses the following URL:\r\nhttps://157.230.28.192/data/\r\nThe following file types were also added to the inclusion list:\r\n.json\r\n.config\r\n.ts\r\n.cs\r\n.js\r\n.aspx\r\n.pst\r\nIn addition to this, Exmatter is configured to skip exfiltration for files with names containing any of the following\r\nstrings:\r\nOneDriveMedTile\r\nlocale-SmallLogo\r\nVisualElements\r\nadobe_sign\r\nAdobe Sign\r\ncore_icons\r\nA fourth variant contained updated SFTP server details:\r\nHost: 159.89.128.13\r\nPort: 22\r\nThe WebDav client used the following updated URL:\r\nhttps://159.89.128.13/data/\r\nFinally, the list of files for inclusion was updated by removing “.png”.\r\nVeteran ransomware operators\r\nhttps://symantec-enterprise-blogs.security.com/blogs/threat-intelligence/blackmatter-data-exfiltration\r\nPage 3 of 4\n\nBlackMatter is linked to the Coreid cyber crime group, which was previously responsible for the Darkside\r\nransomware. For the past 12 months, it has been one of the most prolific targeted ransomware operators and its\r\ntools have been used in a number of ambitious attacks, most notably the May 2021 Darkside attack on Colonial\r\nPipeline that disrupted fuel supplies to the East Coast of the U.S.\r\nCoreid operates under a RaaS model, working with affiliates to conduct ransomware attacks and then taking a\r\nshare of the profits. Like most ransomware actors, attacks linked to Coreid steal victims’ data and the group then\r\nthreatens to publish it to further pressure victims into paying the ransom demand. Whether Exmatter is the\r\ncreation of Coreid itself or one of its affiliates remains to be seen, but its development suggests that data theft and\r\nextortion continues to be a core focus of the group.\r\nProtection/Mitigation\r\nFor the latest protection updates, please visit the Symantec Protection Bulletin.\r\nIndicators of Compromise\r\n325ecd90ce19dd8d184ffe7dfb01b0dd02a77e9eabcb587f3738bcfbd3f832a1\r\n5e355f90b398cbb54829038c6e5d68e8c578405d142bdcc2386cf6161c8d7014\r\n8eded48c166f50be5ac33be4b010b09f911ffc155a3ab76821e4febd369d17ef\r\nb6bc126526e27c98a94aab16989864161db1b3a75f18bd5c72bacbdfccad7bd7\r\nfcaed9faa026a26d00731068e956be39235487f63e0555b71019d16a59ea7e6b\r\n157.230.28.192\r\n159.89.128.13\r\n165.22.84.147\r\nSource: https://symantec-enterprise-blogs.security.com/blogs/threat-intelligence/blackmatter-data-exfiltration\r\nhttps://symantec-enterprise-blogs.security.com/blogs/threat-intelligence/blackmatter-data-exfiltration\r\nPage 4 of 4", "extraction_quality": 1, "language": "EN", "sources": [ "Malpedia", "ETDA" ], "references": [ "https://symantec-enterprise-blogs.security.com/blogs/threat-intelligence/blackmatter-data-exfiltration" ], "report_names": [ "blackmatter-data-exfiltration" ], "threat_actors": [ { "id": "bb8702c5-52ac-4359-8409-998a7cc3eeaf", "created_at": "2023-01-06T13:46:38.405479Z", "updated_at": "2026-04-10T02:00:02.961112Z", "deleted_at": null, "main_name": "FIN7", "aliases": [ "ATK32", "G0046", "G0008", "Sangria Tempest", "ELBRUS", "GOLD NIAGARA", "Coreid", "Carbanak", "Carbon Spider", "JokerStash", "CARBON SPIDER" ], "source_name": "MISPGALAXY:FIN7", "tools": [], "source_id": "MISPGALAXY", "reports": null } ], "ts_created_at": 1775434053, "ts_updated_at": 1775791746, "ts_creation_date": 0, "ts_modification_date": 0, "files": { "pdf": "https://archive.orkl.eu/6d767cfdcb90be3ef47a2c754ddefd651bd8c184.pdf", "text": "https://archive.orkl.eu/6d767cfdcb90be3ef47a2c754ddefd651bd8c184.txt", "img": "https://archive.orkl.eu/6d767cfdcb90be3ef47a2c754ddefd651bd8c184.jpg" } }