# 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.