Query: Sigma rule for Detects suspicious base64 encoded and obfuscated "LOAD" keyword used in .NET "reflection.assembly"
Matching passage: Sigma rule: Detects suspicious base64 encoded and obfuscated "LOAD" keyword used in .NET "reflection.assembly". Logsource: windows / process_creation. Rule: title: Suspicious Encoded And Obfuscated Reflection Assembly Load Function Call id: 9c0295ce-d60d-40bd-bd74-84673b7592b1 related: - id: 62b7ccc9-23b4-471e-aa15-6da3663c4d59 type: similar status: test description: Detects suspicious base64 encoded and obfuscated "LOAD" keyword used in .NET "reflection.assembly" references: - https://github.com/Neo23x0/Raccine/blob/20a569fa21625086433dcce8bb2765d0ea08dcb6/yara/mal_revil.yar - https://thedfirreport.com/2022/05/09/seo-poisoning-a-gootloader-story/ - https://learn.microsoft.com/en-us/dotnet/api/system.appdomain.load?view=net-7.0 author: pH-T (Nextron Systems) date: 2022-03-01 modified: 2023-04-06 tags: - attack.execution - attack.stealth - attack.t1059.001 - attack.t1027 logsource: category: process_creation product: windows detection: selection: CommandLine|contains: - OgA6ACgAIgBMACIAKwAiAG8AYQBkACIAKQ - oAOgAoACIATAAiACsAIgBvAGEAZAAiACkA - 6ADoAKAAiAEwAIgArACIAbwBhAGQAIgApA - OgA6ACgAIgBMAG8AIgArACIAYQBkACIAKQ - oAOgAoACIATABvACIAKwAiAGEAZAAiACkA - 6ADoAKAAiAEwAbwAiACsAIgBhAGQAIgApA - OgA6ACgAIgBMAG8AYQAiACsAIgBkACIAKQ - oAOgAoACIATABvAGEAIgArACIAZAAiACkA - 6ADoAKAAiAEwAbwBhACIAKwAiAGQAIgApA - OgA6ACgAJwBMACcAKwAnAG8AYQBkACcAKQ - oAOgAoACcATAAnACsAJwBvAGEAZAAnACkA - 6ADoAKAAnAEwAJwArACcAbwBhAGQAJwApA - OgA6ACgAJwBMAG8AJwArACcAYQBkACcAKQ - oAOgAoACcATABvACcAKwAnAGEAZAAnACkA - 6ADoAKAAnAEwAbwAnACsAJwBhAGQAJwApA - OgA6ACgAJwBMAG8AYQAnACsAJwBkACcAKQ - oAOgAoACcATABvAGEAJwArACcAZAAnACkA - 6ADoAKAAnAEwAbwBhACcAKwAnAGQAJwApA condition: selection falsepositives: - Unlikely level: high
Near-miss passage: Sigma rule: Detects the suspicious use of the Velociraptor DFIR tool to execute other tools or download additional payloads, as seen. Logsource: windows / process_creation. Rule: title: Suspicious Velociraptor Child Process id: 4bc90587-e6ca-4b41-be0b-ed4d04e4ed0c status: experimental description: Detects the suspicious use of the Velociraptor DFIR tool to execute other tools or download additional payloads, as seen in a campaign where it was abused for remote access and to stage further attacks. references: - https://news.sophos.com/en-us/2025/08/26/velociraptor-incident-response-tool-abused-for-remote-access/ author: Swachchhanda Shrawan Poudel (Nextron Systems) date: 2025-08-29 tags: - attack.command-and-control - attack.persistence - attack.t1219 logsource: category: process_creation product: windows detection: selection_parent: ParentImage|endswith: \Velociraptor.exe selection_child_vscode_tunnel: CommandLine|contains|all: - code.exe - tunnel - --accept-server-license-terms selection_child_msiexec: CommandLine|contains|all: - msiexec - /i - http selection_child_powershell: Image|endswith: - \powershell.exe - \powershell_ise.exe - \pwsh.exe CommandLine|contains: - 'Invoke-WebRequest ' - 'IWR ' - .DownloadFile - .DownloadString condition: selection_parent and 1 of selection_child_* falsepositives: - Legitimate administrators or incident responders might use Velociraptor to execute scripts or tools. However, the combination of Velociraptor spawning these specific processes with these command lines is suspicious. Tuning may be required to exclude known administrative actions or specific scripts. level: high