Query: rule covering Detects suspicious malformed user agent strings in proxy logs
Matching passage: Sigma rule: Detects suspicious malformed user agent strings in proxy logs. Logsource: proxy. Rule: title: Suspicious User Agent id: 7195a772-4b3f-43a4-a210-6a003d65caa1 status: test description: Detects suspicious malformed user agent strings in proxy logs references: - https://github.com/fastly/waf_testbed/blob/8bfc406551f3045e418cbaad7596cff8da331dfc/templates/default/scanners-user-agents.data.erb author: Florian Roth (Nextron Systems) date: 2017-07-08 modified: 2022-10-31 tags: - attack.command-and-control - attack.t1071.001 logsource: category: proxy detection: selection1: c-useragent|startswith: - user-agent - 'Mozilla/3.0 ' - 'Mozilla/2.0 ' - 'Mozilla/1.0 ' - 'Mozilla ' - ' Mozilla/' - Mozila/ - Mozilla/4.0 (compatible; MSIE 6.0; MS Web Services Client Protocol selection2: c-useragent|contains: - ' (compatible;MSIE ' - '.0;Windows NT ' - loader selection3: c-useragent: - _ - CertUtil URL Agent - Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:60.0) - Mozilla/5.0 (Windows NT 6.3; WOW64; rv:28.0) Gecko/20100101 Firefox/28.0 - HTTPS - Erbium-UA-4ce7c27cb4be9d32e333bf032c88235a - x - xxx falsepositives: - c-useragent: Mozilla/3.0 * Acrobat * - cs-host|endswith: - .acrobat.com - .adobe.com - .adobe.io condition: 1 of selection* and not falsepositives falsepositives: - Unknown level: high
Near-miss passage: Sigma rule: Detects changes to the Internet Explorer "DisableFirstRunCustomize" value, which prevents Internet Explorer from running. Logsource: windows / registry_set. Rule: title: Internet Explorer DisableFirstRunCustomize Enabled id: ab567429-1dfb-4674-b6d2-979fd2f9d125 status: test description: 'Detects changes to the Internet Explorer "DisableFirstRunCustomize" value, which prevents Internet Explorer from running the first run wizard the first time a user starts the browser after installing Internet Explorer or Windows. ' references: - https://www.ncsc.gov.uk/static-assets/documents/malware-analysis-reports/devil-bait/NCSC-MAR-Devil-Bait.pdf - https://unit42.paloaltonetworks.com/operation-ke3chang-resurfaces-with-new-tidepool-malware/ - https://admx.help/?Category=InternetExplorer&Policy=Microsoft.Policies.InternetExplorer::NoFirstRunCustomise author: Nasreddine Bencherchali (Nextron Systems) date: 2023-05-16 modified: 2025-10-07 tags: - attack.defense-impairment logsource: product: windows category: registry_set detection: selection: TargetObject|endswith: \Microsoft\Internet Explorer\Main\DisableFirstRunCustomize Details: - DWORD (0x00000001) - DWORD (0x00000002) filter_main_generic: Image: - C:\Windows\explorer.exe - C:\Windows\System32\ie4uinit.exe filter_optional_avira: Image|contains|all: - \Temp\ - \.cr\avira_ Details|contains: DWORD (0x00000001) filter_optional_foxit: Image: - C:\Program Files (x86)\Foxit Software\Foxit PDF Reader\FoxitPDFReader.exe - C:\Program Files\Foxit Software\Foxit PDF Reader\FoxitPDFReader.exe Details|contains: DWORD (0x00000001) condition: selection and not 1 of filter_main_* and not 1 of filter_optional_* falsepositives: - As this is controlled by group policy as well as user settings. Some false positives may occur. level: medium