T1218 — System Binary Proxy Execution

# T1218 - System Binary Proxy Execution

## SOC Recommendation
Investigate System Binary Proxy Execution activity in the context of Stealth: confirm scope, affected host/identity, and whether it matches expected administrative behaviour before deciding this is benign.

## D3FEND Mappings
| D3FEND Technique | Relationship | Practical SOC Action |
|---|---|---|
| File Analysis | Detect | Monitor for File Analysis indicators relevant to this technique. |
| File Encryption | Harden | Apply File Encryption to reduce this technique's viability before an incident occurs. |
| File Eviction | Evict | Use File Eviction to remove the adversary's foothold once this technique is confirmed. |
| Content Filtering | Isolate | Apply Content Filtering to contain the blast radius once this technique is observed. |

## Investigation Steps
1. Review Defender for Endpoint / Defender XDR alerts and timeline for the affected host or identity.
2. Check Sentinel analytics rules and incidents correlated with this technique.
3. Review Entra ID sign-in and audit logs if the technique involves an identity or cloud resource.

## Evidence to Collect
- Host or resource affected
- Account or identity involved
- Timestamp of the activity
- Related process, file, or network artifact
- Any preceding or follow-on alerts

## Response Actions
| Action | Risk | Automation Safe | Approval Required |
|---|---|---|---|
| Kill the LOLBin process via MDE Live Response | Low | No | Yes |
| Block the download URL/IP in MDE custom indicators | Medium | No | Yes |
| Block execution of the specific LOLBin if not needed in the | Medium | No | Yes |

## KQL
```kql
DeviceProcessEvents
| where TimeGenerated >= ago(5m)
| where (FileName =~ "regsvr32.exe" and ProcessCommandLine has_any ("/s", "/u", "/n", "/i:http", "/i:ftp", ".sct", ".dll"))
    or (FileName =~ "mshta.exe" and ProcessCommandLine has_any ("http://", "https://", "ftp://", "javascript:", "vbscript:"))
    or (FileName =~ "certutil.exe" and ProcessCommandLine has_any ("-urlcache", "-decode", "-decodehex", "-ping", "http", "ftp"))
    or (FileName =~ "installutil.exe" and ProcessCommandLine has_any ("/logfile=", "/LogToConsole=false"))
    or (FileName =~ "msbuild.exe" and ProcessCommandLine has_any (".xml", ".csproj", ".proj") and not(FolderPath has "Program Files"))
    or (FileName =~ "cmstp.exe" and ProcessCommandLine has_any ("/s", ".inf"))
    or (FileName =~ "rundll32.exe" and ProcessCommandLine has_any ("javascript:", "vbscript:", "shell32", "http", "https"))
    or (FileName =~ "wmic.exe" and ProcessCommandLine has_any ("process call create", "os get /format:", "http", "ftp"))
| project
    TimeGenerated,
    DeviceName,
    AccountName,
    FileName,
    ProcessCommandLine,
    InitiatingProcessFileName,
    SHA256,
    FolderPath
| extend timestamp = TimeGenerated,
         HostCustomEntity = DeviceName,
         AccountCustomEntity = AccountName
| order by TimeGenerated desc
```
```kql
// File Hash Indicators with Monitor Action and Malware
let timeFrame = 5m;
CyfirmaIndicators_CL 
| where ConfidenceScore >= 80
    and TimeGenerated between (ago(timeFrame) .. now())
    and pattern contains 'file:hashes' and RecommendedActions has 'Monitor' and (Roles contains 'Malware')
| extend MD5 = extract(@"file:hashes\.md5\s*=\s*'([a-fA-F0-9]{32})'", 1, pattern)
| extend SHA1 = extract(@"file:hashes\.'SHA-1'\s*=\s*'([a-fA-F0-9]{40})'", 1, pattern)
| extend SHA256 = extract(@"file:hashes\.'SHA-256'\s*=\s*'([a-fA-F0-9]{64})'", 1, pattern)
| extend
    Algo_MD5='md5',
    Algo_SHA1= 'SHA1',
    Algo_SHA256='SHA256',
    ProviderName = 'CYFIRMA',
    ProductName = 'DeCYFIR/DeTCT'
| project  
    MD5,
    Algo_MD5,
    SHA1,
    Algo_SHA1,
    SHA256,
    Algo_SHA256,
    ThreatActors,
    Sources,
    RecommendedActions,
    Roles,
    Country,
    name,
    Description,
    ConfidenceScore,
    SecurityVendors,
    IndicatorID,
    created,
    modified,
    valid_from,
    Tags,
    ThreatType,
    TimeGenerated,
    ProductName,
    ProviderName
```
```kql
DeviceImageLoadEvents 
| where InitiatingProcessFileName has_any ("rundll32.exe","regsvr32.exe")
| where FileName !endswith ".dll"
| join (
DeviceNetworkEvents
| where InitiatingProcessFileName has_any ("rundll32.exe","regsvr32.exe")
| where RemoteIPType == "Public"
) on InitiatingProcessFileName, InitiatingProcessId, InitiatingProcessCreationTime, InitiatingProcessCommandLine
| project TimeGenerated, DeviceName, FileName, FolderPath, SHA1, InitiatingProcessFileName, InitiatingProcessCommandLine, LocalIP, LocalPort, RemoteIP, RemoteUrl, RemotePort, InitiatingProcessParentFileName
| extend HostName = iff(DeviceName has '.', substring(DeviceName, 0, indexof(DeviceName, '.')), DeviceName)
| extend DnsDomain = iff(DeviceName has '.', substring(DeviceName, indexof(DeviceName, '.') + 1), "")
```

## Escalation Criteria
- System Binary Proxy Execution activity observed on a privileged account or critical system.
- Activity follows or precedes other suspicious behaviour in the same investigation.
- Automated triage cannot confidently rule out malicious intent.

## False Positive Considerations
- Legitimate administrative or maintenance activity matching this pattern.
- Approved security testing or red team exercise.
- Known benign software producing similar telemetry.

Generated by SOC Response Atlas by Basyrix.

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• /api/techniques/T1218.json
• /api/recommendations/T1218.json
• /api/d3fend/T1218.json
• /api/mappings/T1218.json
• /api/confluence/T1218.md

Example curl:

curl https://atlas.basyrix.com/api/recommendations/T1218.json

Response:

{
  "technique_id": "T1218",
  "name": "System Binary Proxy Execution",
  "priority": "high",
  "status": "complete",
  "version": "0.1.0",
  "last_reviewed": "2026-07-23",
  "generated_by": "SOC Response Atlas by Basyrix",
  "tactics": [
    "Stealth"
  ],
  "platforms": [
    "Linux",
    "macOS",
    "Windows"
  ],
  "summary": "Adversaries may bypass process and/or signature-based defenses by proxying execution of malicious content with signed, or otherwise trusted, binaries. Binaries used in this technique are often Microsoft-signed files, indicating that they have been either downloaded from Microsoft or are already native in the operating system. Binaries signed with trusted digital certificates can typically execute on Windows systems protected by digital signature validation...",
  "soc_recommendation": "Investigate System Binary Proxy Execution activity in the context of Stealth: confirm scope, affected host/identity, and whether it matches expected administrative behaviour before deciding this is benign.",
  "d3fend_mappings": [
    {
      "id": "D3-FA",
      "name": "File Analysis",
      "relationship": "detect",
      "practical_action": "Monitor for File Analysis indicators relevant to this technique.",
      "tooling": [
        "Defender for Endpoint"
      ]
    },
    {
      "id": "D3-FE",
      "name": "File Encryption",
      "relationship": "harden",
      "practical_action": "Apply File Encryption to reduce this technique's viability before an incident occurs.",
      "tooling": [
        "Defender for Endpoint"
      ]
    },
    {
      "id": "D3-FEV",
      "name": "File Eviction",
      "relationship": "evict",
      "practical_action": "Use File Eviction to remove the adversary's foothold once this technique is confirmed.",
      "tooling": [
        "Defender for Endpoint"
      ]
    },
    {
      "id": "D3-CF",
      "name": "Content Filtering",
      "relationship": "isolate",
      "practical_action": "Apply Content Filtering to contain the blast radius once this technique is observed.",
      "tooling": [
        "Defender for Endpoint"
      ]
    }
  ],
  "investigation_steps": {
    "microsoft": [
      "Review Defender for Endpoint / Defender XDR alerts and timeline for the affected host or identity.",
      "Check Sentinel analytics rules and incidents correlated with this technique.",
      "Review Entra ID sign-in and audit logs if the technique involves an identity or cloud resource."
    ],
    "generic": [
      "Confirm whether the observed system binary proxy execution activity matches expected administrative or application behaviour.",
      "Identify the host, account, or resource where the activity occurred and its business criticality.",
      "Check for related alerts before and after this activity to reconstruct the broader intrusion timeline.",
      "Real detection reference: \"System Binary Proxy Execution (LOLBins)\" -- Flags execution of trusted, signed Windows binaries (regsvr32, mshta, certutil, installutil, msbuild, cmstp, rundll32, wmic) in patterns consistent with LOLBin abuse to bypass application whitelisting."
    ]
  },
  "evidence_to_collect": [
    "Host or resource affected",
    "Account or identity involved",
    "Timestamp of the activity",
    "Related process, file, or network artifact",
    "Any preceding or follow-on alerts"
  ],
  "response_actions": [
    {
      "name": "Kill the LOLBin process via MDE Live Response",
      "category": "Response",
      "risk": "Low",
      "automation_safe": false,
      "approval_required": true,
      "tool": "Defender for Endpoint"
    },
    {
      "name": "Block the download URL/IP in MDE custom indicators",
      "category": "Response",
      "risk": "Medium",
      "automation_safe": false,
      "approval_required": true,
      "tool": "Defender for Endpoint"
    },
    {
      "name": "Block execution of the specific LOLBin if not needed in the",
      "category": "Response",
      "risk": "Medium",
      "automation_safe": false,
      "approval_required": true,
      "tool": "See investigation guide",
      "notes": "Block execution of the specific LOLBin if not needed in the environment (via AppLocker/WDAC)"
    }
  ],
  "queries": {
    "kql": [
      {
        "name": "GEN-DE-003 — System Binary Proxy Execution (LOLBins)",
        "description": "Flags execution of trusted, signed Windows binaries (regsvr32, mshta, certutil, installutil, msbuild, cmstp, rundll32, wmic) in patterns consistent with LOLBin abuse to bypass application whitelisting. (Source: Bell Integration baseline detection library.)",
        "query": "DeviceProcessEvents\n| where TimeGenerated >= ago(5m)\n| where (FileName =~ \"regsvr32.exe\" and ProcessCommandLine has_any (\"/s\", \"/u\", \"/n\", \"/i:http\", \"/i:ftp\", \".sct\", \".dll\"))\n    or (FileName =~ \"mshta.exe\" and ProcessCommandLine has_any (\"http://\", \"https://\", \"ftp://\", \"javascript:\", \"vbscript:\"))\n    or (FileName =~ \"certutil.exe\" and ProcessCommandLine has_any (\"-urlcache\", \"-decode\", \"-decodehex\", \"-ping\", \"http\", \"ftp\"))\n    or (FileName =~ \"installutil.exe\" and ProcessCommandLine has_any (\"/logfile=\", \"/LogToConsole=false\"))\n    or (FileName =~ \"msbuild.exe\" and ProcessCommandLine has_any (\".xml\", \".csproj\", \".proj\") and not(FolderPath has \"Program Files\"))\n    or (FileName =~ \"cmstp.exe\" and ProcessCommandLine has_any (\"/s\", \".inf\"))\n    or (FileName =~ \"rundll32.exe\" and ProcessCommandLine has_any (\"javascript:\", \"vbscript:\", \"shell32\", \"http\", \"https\"))\n    or (FileName =~ \"wmic.exe\" and ProcessCommandLine has_any (\"process call create\", \"os get /format:\", \"http\", \"ftp\"))\n| project\n    TimeGenerated,\n    DeviceName,\n    AccountName,\n    FileName,\n    ProcessCommandLine,\n    InitiatingProcessFileName,\n    SHA256,\n    FolderPath\n| extend timestamp = TimeGenerated,\n         HostCustomEntity = DeviceName,\n         AccountCustomEntity = AccountName\n| order by TimeGenerated desc"
      },
      {
        "name": "c919c911-8b01-44f8-9c3b-60b1edfc417f — CYFIRMA - High severity File Hash Indicators with Monitor Action and Malware",
        "description": "\"This KQL query retrieves file hash indicators (MD5, SHA1, SHA256) from the CyfirmaIndicators_CL table within the last 5 minutes. It filters records with a confidence score of 80 or higher, containing file hash patterns, a recommended action of 'Monitor', and roles marked as 'Malware'. Extracted hashes and key threat intelligence details are projected for monitoring and investigation.\" (Source: Microsoft's official Azure-Sentinel Detections (MIT licensed).)",
        "query": "// File Hash Indicators with Monitor Action and Malware\nlet timeFrame = 5m;\nCyfirmaIndicators_CL \n| where ConfidenceScore >= 80\n    and TimeGenerated between (ago(timeFrame) .. now())\n    and pattern contains 'file:hashes' and RecommendedActions has 'Monitor' and (Roles contains 'Malware')\n| extend MD5 = extract(@\"file:hashes\\.md5\\s*=\\s*'([a-fA-F0-9]{32})'\", 1, pattern)\n| extend SHA1 = extract(@\"file:hashes\\.'SHA-1'\\s*=\\s*'([a-fA-F0-9]{40})'\", 1, pattern)\n| extend SHA256 = extract(@\"file:hashes\\.'SHA-256'\\s*=\\s*'([a-fA-F0-9]{64})'\", 1, pattern)\n| extend\n    Algo_MD5='md5',\n    Algo_SHA1= 'SHA1',\n    Algo_SHA256='SHA256',\n    ProviderName = 'CYFIRMA',\n    ProductName = 'DeCYFIR/DeTCT'\n| project  \n    MD5,\n    Algo_MD5,\n    SHA1,\n    Algo_SHA1,\n    SHA256,\n    Algo_SHA256,\n    ThreatActors,\n    Sources,\n    RecommendedActions,\n    Roles,\n    Country,\n    name,\n    Description,\n    ConfidenceScore,\n    SecurityVendors,\n    IndicatorID,\n    created,\n    modified,\n    valid_from,\n    Tags,\n    ThreatType,\n    TimeGenerated,\n    ProductName,\n    ProviderName"
      },
      {
        "name": "36fbd4e7-5630-4414-aa42-702a7fdded21 — Regsvr32 Rundll32 Image Loads Abnormal Extension",
        "description": "This query is looking for regsvr32.exe or rundll32.exe loading DLL images with other extensions than .dll. Joins the data to public network events. References: https://threathunt.blog/running-live-malware-for-threat-hunting-purposes/ (Source: Microsoft's official Azure-Sentinel Detections (MIT licensed), mapped via sub-technique T1218.011.)",
        "query": "DeviceImageLoadEvents \n| where InitiatingProcessFileName has_any (\"rundll32.exe\",\"regsvr32.exe\")\n| where FileName !endswith \".dll\"\n| join (\nDeviceNetworkEvents\n| where InitiatingProcessFileName has_any (\"rundll32.exe\",\"regsvr32.exe\")\n| where RemoteIPType == \"Public\"\n) on InitiatingProcessFileName, InitiatingProcessId, InitiatingProcessCreationTime, InitiatingProcessCommandLine\n| project TimeGenerated, DeviceName, FileName, FolderPath, SHA1, InitiatingProcessFileName, InitiatingProcessCommandLine, LocalIP, LocalPort, RemoteIP, RemoteUrl, RemotePort, InitiatingProcessParentFileName\n| extend HostName = iff(DeviceName has '.', substring(DeviceName, 0, indexof(DeviceName, '.')), DeviceName)\n| extend DnsDomain = iff(DeviceName has '.', substring(DeviceName, indexof(DeviceName, '.') + 1), \"\")"
      }
    ],
    "spl": [],
    "esql": [
      {
        "name": "6756ee27-9152-479b-9b73-54b5bbda301c — Rare Connection to WebDAV Target",
        "description": "(ESQL) Identifies rare connection attempts to a Web Distributed Authoring and Versioning (WebDAV) resource. Attackers may inject WebDAV paths in files or features opened by a victim user to leak their NTLM credentials via forced authentication. (Source: Elastic's official detection-rules repository (Elastic License v2).)",
        "query": "from logs-endpoint.events.process-*, logs-windows.sysmon_operational-*, logs-system.security-*, logs-windows.*, winlogbeat-*, logs-crowdstrike.fdr*, logs-m365_defender.event-* METADATA _id, _version, _index\n| where\n    event.category == \"process\" and\n    event.type == \"start\" and\n    process.name == \"rundll32.exe\" and\n    process.command_line like \"*DavSetCookie*\"\n| keep host.id, process.command_line, user.name, user.id\n// extract domain or IP address from process cmdline\n| grok process.command_line \"\"\"(?<Esql.server_webdav_server>((http|https)://[a-zA-Z0-9-\\.]{1,}\\.[a-zA-Z]{2,3}[@\\/]+)|(\\b(?:(?:25[0-5]|2[0-4]\\d|1\\d\\d|[1-9]?\\d)\\.){3}(?:25[0-5]|2[0-4]\\d|1\\d\\d|[1-9]?\\d)\\b)[@\\/]+)\"\"\"\n// remove sub domains from URL\n| eval Esql.server_webdav_server = REPLACE(Esql.server_webdav_server, \"\"\"((http|https)://[a-zA-Z0-9-]{1,}\\.)\"\"\", \"\")\n| eval Esql.server_webdav_server = REPLACE(Esql.server_webdav_server, \"/\", \"\")\n| where\n    Esql.server_webdav_server is not null and\n    not Esql.server_webdav_server in (\"www.google.com\", \"www.elastic.co\", \"sharepoint.com\", \"live.net\", \"google.com\", \"SHAREPOINT.COM\", \"github.com\") and\n    // excludes private IP ranges\n    not Esql.server_webdav_server rlike \"\"\"(10\\.(\\d{1,3}\\.){2}\\d{1,3}|172\\.(1[6-9]|2\\d|3[0-1])\\.(\\d{1,3}\\.)\\d{1,3}|192\\.168\\.(\\d{1,3}\\.)\\d{1,3})\"\"\"\n| stats\n    Esql.event_count = count(*),\n    Esql.host_id_count_distinct = count_distinct(host.id),\n    Esql.host_id_values = values(host.id),\n    Esql.user_name_values = values(user.name)\n  by Esql.server_webdav_server\n| where\n    Esql.host_id_count_distinct == 1 and Esql.event_count <= 3\n| eval host.id = MV_MIN(Esql.host_id_values), user.name = MV_MIN(Esql.user_name_values), destination.domain = MV_MIN(Esql.server_webdav_server)\n| KEEP host.id, user.name, destination.domain, Esql.*"
      },
      {
        "name": "e516bf56-d51b-43e8-91ec-9e276331f433 — Network Activity to a Suspicious Top Level Domain",
        "description": "(EQL) Identifies DNS queries to commonly abused Top Level Domains by common LOLBINs or executables running from world writable directories or unsigned binaries. This behavior matches on common malware C2 abusing less formal domain names. (Source: Elastic's official detection-rules repository (Elastic License v2).)",
        "query": "network where host.os.type == \"windows\" and dns.question.name != null and\n (\n  process.name : (\"MSBuild.exe\", \"mshta.exe\", \"wscript.exe\", \"powershell.exe\", \"pwsh.exe\", \"msiexec.exe\", \"rundll32.exe\",\n                  \"bitsadmin.exe\", \"InstallUtil.exe\", \"python.exe\", \"regsvr32.exe\", \"dllhost.exe\", \"node.exe\", \"curl.exe\",\n                  \"java.exe\", \"javaw.exe\", \"*.pif\", \"*.com\", \"*.scr\") or\n  (?process.code_signature.trusted == false or ?process.code_signature.exists == false) or\n  ?process.code_signature.subject_name : (\"AutoIt Consulting Ltd\", \"OpenJS Foundation\", \"Python Software Foundation\") or\n  ?process.executable : (\n    \"?:\\\\Users\\\\Public\\\\*.exe\", \"?:\\\\ProgramData\\\\*.exe\", \"?:\\\\Users\\\\*\\\\Downloads\\\\*.exe\",\n    \"\\\\Device\\\\HarddiskVolume*\\\\Users\\\\Public\\\\*.exe\", \"\\\\Device\\\\HarddiskVolume*\\\\ProgramData\\\\*.exe\", \"\\\\Device\\\\HarddiskVolume*\\\\Users\\\\*\\\\Downloads\\\\*.exe\"\n  )\n ) and\ndns.question.name regex \"\"\".*\\.(top|buzz|xyz|rest|ml|cf|gq|ga|onion|monster|cyou|quest|cc|bar|cfd|click|cam|surf|tk|shop|club|icu|pw|ws|online|fun|life|boats|store|hair|skin|motorcycles|christmas|lol|makeup|mom|bond|beauty|biz|live|work|zip|country|accountant|date|party|science|loan|win|men|faith|review|racing|download|host|zone)\"\"\" and\n\nnot process.executable : (\n    \"?:\\\\ProgramData\\\\Microsoft\\\\Windows Defender\\\\platform\\\\*\\\\*.exe\",\n    \"\\\\Device\\\\HarddiskVolume*\\\\ProgramData\\\\Microsoft\\\\Windows Defender\\\\platform\\\\*\\\\*.exe\"\n)"
      }
    ]
  },
  "automation": {
    "safe": [
      "Add recommendation as Sentinel incident comment.",
      "Run enrichment queries.",
      "Create ServiceNow SecOps task."
    ],
    "approval_required": [
      "Contain or disable the affected host/account.",
      "Any change to production configuration."
    ]
  },
  "escalation_criteria": [
    "System Binary Proxy Execution activity observed on a privileged account or critical system.",
    "Activity follows or precedes other suspicious behaviour in the same investigation.",
    "Automated triage cannot confidently rule out malicious intent."
  ],
  "false_positive_considerations": [
    "Legitimate administrative or maintenance activity matching this pattern.",
    "Approved security testing or red team exercise.",
    "Known benign software producing similar telemetry."
  ],
  "confluence": {
    "title": "T1218 - System Binary Proxy Execution Response Guidance",
    "labels": [
      "mitre",
      "attack",
      "d3fend",
      "secops",
      "basyrix"
    ],
    "sections": [
      "summary",
      "d3fend_mappings",
      "investigation_steps",
      "response_actions",
      "queries",
      "automation",
      "escalation_criteria",
      "false_positive_considerations"
    ]
  }
}