Query: alert when Detects remote RPC calls to possibly abuse remote encryption service via MS-EFSR
Matching passage: Sigma rule: Detects remote RPC calls to possibly abuse remote encryption service via MS-EFSR. Logsource: rpc_firewall / application. Rule: title: Remote Encrypting File System Abuse id: 5f92fff9-82e2-48eb-8fc1-8b133556a551 status: test description: Detects remote RPC calls to possibly abuse remote encryption service via MS-EFSR references: - https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36942 - https://github.com/jsecurity101/MSRPC-to-ATTACK/blob/ddd4608fe8684fcf2fcf9b48c5f0b3c28097f8a3/documents/MS-EFSR.md - https://github.com/zeronetworks/rpcfirewall - https://zeronetworks.com/blog/stopping-lateral-movement-via-the-rpc-firewall/ author: Sagie Dulce, Dekel Paz date: 2022-01-01 tags: - attack.lateral-movement logsource: product: rpc_firewall category: application definition: 'Requirements: install and apply the RPC Firewall to all processes with "audit:true action:block uuid:df1941c5-fe89-4e79-bf10-463657acf44d or c681d488-d850-11d0-8c52-00c04fd90f7e' detection: selection: EventLog: RPCFW EventID: 3 InterfaceUuid: - df1941c5-fe89-4e79-bf10-463657acf44d - c681d488-d850-11d0-8c52-00c04fd90f7e condition: selection falsepositives: - Legitimate usage of remote file encryption level: high
Near-miss passage: Sigma rule: Detects the use of curl with NTLM authentication and empty credentials (-u :), which can be abused to leak the currently. Logsource: windows / process_creation. Rule: title: NTLM Hash Leak Via Curl NTLM Authentication id: 916eb839-895e-47f8-99ee-3008bf377a3e status: test description: 'Detects the use of curl with NTLM authentication and empty credentials (-u :), which can be abused to leak the currently logged-in user''s NTLMv2 challenge-response to an attacker-controlled server, enabling offline cracking or relay attacks. When no credentials are provided, the Microsoft-shipped curl passes a NULL identity to Windows SSPI, which automatically falls back to the current user''s logon session credentials stored in LSASS — without requiring a plaintext password. This behavior is exclusive to the curl binary shipped by Microsoft (available since Windows 10 / Windows Server 2019), which is built with SSPI support. ' references: - https://github.com/curl/curl/blob/master/lib/vauth/ntlm_sspi.c#L128-L140 - https://learn.microsoft.com/en-us/windows/win32/secauthn/acquirecredentialshandle--ntlm - https://curl.se/docs/manpage.html#--ntlm author: Swachchhanda Shrawan Poudel (Nextron Systems) date: 2026-06-04 tags: - attack.credential-access - attack.t1187 logsource: category: process_creation product: windows detection: selection_img: - Image|endswith: \curl.exe - OriginalFileName: curl.exe selection_ntlm_flag: CommandLine|contains: --ntlm selection_empty_creds: CommandLine|re: '(?i)\s(-u|--user)\s*:' condition: all of selection_* falsepositives: - Should be very rare as it's not widely known or used, but could occur in legitimate use cases where curl is used with NTLM authentication and empty credentials, such as in certain scripts or automation tasks. level: high regression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_curl_ntlm_hash_leak_attempt/info.yml