Query: write Sigma for Detects changes to the "MaxMpxCt" registry value. MaxMpxCt specifies the maximum outstanding network requests for the se
Matching passage: Sigma rule: Detects changes to the "MaxMpxCt" registry value. MaxMpxCt specifies the maximum outstanding network requests for the se. Logsource: windows / registry_set. Rule: title: MaxMpxCt Registry Value Changed id: 0e6a9e62-627e-496c-aef5-bfa39da29b5e status: test description: 'Detects changes to the "MaxMpxCt" registry value. MaxMpxCt specifies the maximum outstanding network requests for the server per client, which is used when negotiating a Server Message Block (SMB) connection with a client. Note if the value is set beyond 125 older Windows 9x clients will fail to negotiate. Ransomware threat actors and operators (specifically BlackCat) were seen increasing this value in order to handle a higher volume of traffic. ' references: - https://www.huntress.com/blog/blackcat-ransomware-affiliate-ttps - https://securityscorecard.com/research/deep-dive-into-alphv-blackcat-ransomware - https://www.intrinsec.com/alphv-ransomware-gang-analysis/?cn-reloaded=1 - https://www.sentinelone.com/labs/blackcat-ransomware-highly-configurable-rust-driven-raas-on-the-prowl-for-victims/ author: Nasreddine Bencherchali (Nextron Systems) date: 2024-03-19 tags: - attack.stealth - attack.t1070.005 logsource: category: registry_set product: windows detection: selection: TargetObject|endswith: \Services\LanmanServer\Parameters\MaxMpxCt condition: selection falsepositives: - Unknown level: low
Near-miss passage: Sigma rule: Shadow Copies deletion using operating systems utilities. Logsource: windows / process_creation. Rule: title: Shadow Copies Deletion Using Operating Systems Utilities id: c947b146-0abc-4c87-9c64-b17e9d7274a2 status: stable description: Shadow Copies deletion using operating systems utilities references: - https://www.slideshare.net/heirhabarov/hunting-for-credentials-dumping-in-windows-environment - https://blog.talosintelligence.com/2017/05/wannacry.html - https://securingtomorrow.mcafee.com/other-blogs/mcafee-labs/new-teslacrypt-ransomware-arrives-via-spam/ - https://www.bleepingcomputer.com/news/security/why-everyone-should-disable-vssadmin-exe-now/ - https://www.hybrid-analysis.com/sample/ed01ebfbc9eb5bbea545af4d01bf5f1071661840480439c6e5babe8e080e41aa?environmentId=100 - https://github.com/Neo23x0/Raccine#the-process - https://github.com/Neo23x0/Raccine/blob/20a569fa21625086433dcce8bb2765d0ea08dcb6/yara/gen_ransomware_command_lines.yar - https://redcanary.com/blog/intelligence-insights-october-2021/ - https://symantec-enterprise-blogs.security.com/blogs/threat-intelligence/blackbyte-exbyte-ransomware author: Florian Roth (Nextron Systems), Michael Haag, Teymur Kheirkhabarov, Daniil Yugoslavskiy, oscd.community, Andreas Hunkeler (@Karneades) date: 2019-10-22 modified: 2022-11-03 tags: - attack.impact - attack.stealth - attack.t1070 - attack.t1490 logsource: category: process_creation product: windows detection: selection1_img: - Image|endswith: - \powershell.exe - \pwsh.exe - \wmic.exe - \vssadmin.exe - \diskshadow.exe - OriginalFileName: - PowerShell.EXE - pwsh.dll - wmic.exe - VSSADMIN.EXE - diskshadow.exe selection1_cli: CommandLine|contains|all: - shadow - delete selection2_img: - Image|endswith: \wbadmin.exe - OriginalFileName: WBADMIN.EXE selection2_cli: CommandLine|contains|all: - delete - catalog - quiet selection3_img: - Image|endswith: \vssadmin.exe - OriginalFileName: VSSADMIN.EXE selection3_cli: CommandLine|contains|all: - resize - shadowstorage CommandLine|contains: - unbounded - /MaxSize= condition: (all of selection1*) or (all of selection2*) or (all of selection3*) falsepositives: - Legitimate Administrator deletes Shadow Copies using operating systems utilities for legitimate reason - LANDesk LDClient Ivanti-PSModule (PS EncodedCommand) level: high