Potential Credential Dumping Activity Via LSASS

/*
 * Copyright 2025 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

rule potential_credential_dumping_activity_via_lsass {

  meta:
    author = "Samir Bousseaden, Michael Haag"
    description = "Detects process access requests to the LSASS process with specific call trace calls and access masks. This behaviour is expressed by many credential dumping tools such as Mimikatz, NanoDump, Invoke-Mimikatz, Procdump and even the Taskmgr dumping feature."
    reference = "https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_access/proc_access_win_lsass_memdump.yml"
    license = "https://github.com/SigmaHQ/Detection-Rule-License/blob/main/LICENSE.Detection.Rules.md"
    rule_name = "Potential Credential Dumping Activity Via LSASS"
    sigma_uuid = "5ef9853e-4d0e-4a70-846f-a9ca37d876da"
    sigma_status = "experimental"
    rule_id = "mr_33474568-9a0a-4588-ba79-144ab7908f8e"
    tactic = "TA0006"
    technique = "T1003.001"
    type = "Detection"
    data_source = "Sysmon"
    platform = "Windows"
    severity = "Medium"
    priority = "Medium"
    false_positives = "Unknown"

  events:
    $process.metadata.event_type = "PROCESS_OPEN"
    re.regex($process.target.process.file.full_path, `\\lsass\.exe$`) nocase
    (
        strings.contains(strings.to_lower($process.target.resource.name), "0x1038") or
        strings.contains(strings.to_lower($process.target.resource.name), "0x1438") or
        strings.contains(strings.to_lower($process.target.resource.name), "0x143a") or
        strings.contains(strings.to_lower($process.target.resource.name), "0x1fffff") //questionable, this one and others have been filtered out due to FP
    )
    (
        strings.contains(strings.to_lower($process.additional.fields["CallTrace"]), "dbgcore.dll") or
        strings.contains(strings.to_lower($process.additional.fields["CallTrace"]), "dbghelp.dll") or
        strings.contains(strings.to_lower($process.additional.fields["CallTrace"]), "kernel32.dll") or
        strings.contains(strings.to_lower($process.additional.fields["CallTrace"]), "kernelbase.dll") or
        strings.contains(strings.to_lower($process.additional.fields["CallTrace"]), "ntdll.dll")
    )
    NOT (
            strings.contains($process.principal.administrative_domain, "AUTHORI") or
            strings.contains($process.principal.administrative_domain, "AUTORI")
        )
    NOT (
        strings.contains(strings.to_lower($process.additional.fields["CallTrace"]), ":\\windows\\temp\\asgard2-agent\\") and
        strings.contains(strings.to_lower($process.additional.fields["CallTrace"]), "\\thor\\thor64.exe+") and
        strings.contains(strings.to_upper($process.additional.fields["CallTrace"]), "|UNKNOWN(") and
        $process.target.resource.name = "0x103800" nocase
        )
    NOT re.regex($process.principal.process.file.full_path, `:\\Windows\\Sysmon64\.exe$`) nocase
    $process.principal.hostname = $hostname

  match:
    $hostname over 5m

  outcome:
    //example usage of specifying test hostname to adjust risk score
    $risk_score = max(if($process.principal.hostname = "hostname", 0, 15))
    $principal_process_pid = array_distinct($process.principal.process.pid)
    $principal_process_command_line = array_distinct($process.principal.process.command_line)
    $principal_process_file_sha256 = array_distinct($process.principal.process.file.sha256)
    $principal_process_file_full_path = array_distinct($process.principal.process.file.full_path)
    $principal_process_product_specfic_process_id = array_distinct($process.principal.process.product_specific_process_id)
    $principal_process_parent_process_product_specfic_process_id = array_distinct($process.principal.process.parent_process.product_specific_process_id)
    $target_process_pid = array_distinct($process.target.process.pid)
    $target_process_command_line = array_distinct($process.target.process.command_line)
    $target_process_file_sha256 = array_distinct($process.target.process.file.sha256)
    $target_process_file_full_path = array_distinct($process.target.process.file.full_path)
    $target_process_product_specfic_process_id = array_distinct($process.target.process.product_specific_process_id)
    $log_type = array_distinct(strings.concat($process.metadata.log_type,"/",$process.metadata.product_event_type))

  condition:
    $process
}