Potential Build Process Compromise

// How far back to look for events from
let timeframe = 1d;
// How close together build events and file modifications should occur to alert (make this smaller to reduce FPs)
let time_window = 5m;
// Edit this to include build processes used
let build_processes = dynamic(["MSBuild.exe", "dotnet.exe", "VBCSCompiler.exe"]);
// Include any processes that you want to allow to edit files during/around the build process
let allow_list = dynamic([""]);
(union isfuzzy=true
(SecurityEvent
| where TimeGenerated > ago(timeframe)
// Look for build process starts
| where EventID == 4688
| where Process has_any (build_processes)
| summarize by BuildParentProcess=ParentProcessName, BuildProcess=Process, BuildAccount = Account, Computer, BuildCommand=CommandLine, timekey= bin(TimeGenerated, time_window), BuildProcessTime=TimeGenerated
| join kind=inner(
SecurityEvent
| where TimeGenerated > ago(timeframe)
// Look for file modifications to code file
| where EventID == 4663
| where Process !in (allow_list)
// Look for code files, edit this to include file extensions used in build.
| where ObjectName endswith ".cs" or ObjectName endswith ".cpp"
// 0x6 and 0x4 for file append, 0x100 for file replacements
| where AccessMask == "0x6"  or AccessMask == "0x4" or AccessMask == "0X100"
| summarize by FileEditParentProcess=ParentProcessName, FileEditAccount = Account, Computer, FileEdited=ObjectName, FileEditProcess=ProcessName, timekey= bin(TimeGenerated, time_window), FileEditTime=TimeGenerated)
// join where build processes and file modifications seen at same time on same host
on timekey, Computer
// Limit to only where the file edit happens after the build process starts
| where BuildProcessTime <= FileEditTime
| summarize make_set(FileEdited), make_set(FileEditProcess), make_set(FileEditAccount) by timekey, Computer, BuildParentProcess, BuildProcess
),
(WindowsEvent
| where TimeGenerated > ago(timeframe)
// Look for build process starts
| where EventID == 4688 and EventData has_any (build_processes)
| extend NewProcessName = tostring(EventData.NewProcessName)
| extend Process=tostring(split(NewProcessName, '\\')[-1])
| where Process has_any (build_processes)
| extend ParentProcessName = tostring(EventData.ParentProcessName)
| extend Account =  strcat(tostring(EventData.SubjectDomainName),"\\", tostring(EventData.SubjectUserName))
| extend CommandLine = tostring(EventData.CommandLine) 
| summarize by BuildParentProcess=ParentProcessName, BuildProcess=Process, BuildAccount = Account, Computer, BuildCommand=CommandLine, timekey= bin(TimeGenerated, time_window), BuildProcessTime=TimeGenerated
| join kind=inner(
WindowsEvent
| where TimeGenerated > ago(timeframe)
// Look for file modifications to code file
| where EventID == 4663 and EventData has_any ("0x6", "0x4", "0X100") and EventData has_any (".cs", ".cpp")
| extend NewProcessName = tostring(EventData.NewProcessName)
| extend Process=tostring(split(NewProcessName, '\\')[-1])
| where Process !in (allow_list)
// Look for code files, edit this to include file extensions used in build.
| extend ObjectName = tostring(EventData.ObjectName)
| where ObjectName endswith ".cs" or ObjectName endswith ".cpp"
// 0x6 and 0x4 for file append, 0x100 for file replacements
| extend AccessMask = tostring(EventData.AccessMask)  
| where AccessMask == "0x6"  or AccessMask == "0x4" or AccessMask == "0X100"
| extend ParentProcessName = tostring(EventData.ParentProcessName)
| extend Account =  strcat(tostring(EventData.SubjectDomainName),"\\", tostring(EventData.SubjectUserName))
| extend ProcessName = tostring(EventData.ProcessName)
| summarize by FileEditParentProcess=ParentProcessName, FileEditAccount = Account, Computer, FileEdited=ObjectName, FileEditProcess=ProcessName, timekey= bin(TimeGenerated, time_window), FileEditTime=TimeGenerated)
// join where build processes and file modifications seen at same time on same host
on timekey, Computer
// Limit to only where the file edit happens after the build process starts
| where BuildProcessTime <= FileEditTime
| summarize make_set(FileEdited), make_set(FileEditProcess), make_set(FileEditAccount) by timekey, Computer, BuildParentProcess, BuildProcess
))
| extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
| project-away DomainIndex

queryPeriod: 1d
query: |
  // How far back to look for events from
  let timeframe = 1d;
  // How close together build events and file modifications should occur to alert (make this smaller to reduce FPs)
  let time_window = 5m;
  // Edit this to include build processes used
  let build_processes = dynamic(["MSBuild.exe", "dotnet.exe", "VBCSCompiler.exe"]);
  // Include any processes that you want to allow to edit files during/around the build process
  let allow_list = dynamic([""]);
  (union isfuzzy=true
  (SecurityEvent
  | where TimeGenerated > ago(timeframe)
  // Look for build process starts
  | where EventID == 4688
  | where Process has_any (build_processes)
  | summarize by BuildParentProcess=ParentProcessName, BuildProcess=Process, BuildAccount = Account, Computer, BuildCommand=CommandLine, timekey= bin(TimeGenerated, time_window), BuildProcessTime=TimeGenerated
  | join kind=inner(
  SecurityEvent
  | where TimeGenerated > ago(timeframe)
  // Look for file modifications to code file
  | where EventID == 4663
  | where Process !in (allow_list)
  // Look for code files, edit this to include file extensions used in build.
  | where ObjectName endswith ".cs" or ObjectName endswith ".cpp"
  // 0x6 and 0x4 for file append, 0x100 for file replacements
  | where AccessMask == "0x6"  or AccessMask == "0x4" or AccessMask == "0X100"
  | summarize by FileEditParentProcess=ParentProcessName, FileEditAccount = Account, Computer, FileEdited=ObjectName, FileEditProcess=ProcessName, timekey= bin(TimeGenerated, time_window), FileEditTime=TimeGenerated)
  // join where build processes and file modifications seen at same time on same host
  on timekey, Computer
  // Limit to only where the file edit happens after the build process starts
  | where BuildProcessTime <= FileEditTime
  | summarize make_set(FileEdited), make_set(FileEditProcess), make_set(FileEditAccount) by timekey, Computer, BuildParentProcess, BuildProcess
  ),
  (WindowsEvent
  | where TimeGenerated > ago(timeframe)
  // Look for build process starts
  | where EventID == 4688 and EventData has_any (build_processes)
  | extend NewProcessName = tostring(EventData.NewProcessName)
  | extend Process=tostring(split(NewProcessName, '\\')[-1])
  | where Process has_any (build_processes)
  | extend ParentProcessName = tostring(EventData.ParentProcessName)
  | extend Account =  strcat(tostring(EventData.SubjectDomainName),"\\", tostring(EventData.SubjectUserName))
  | extend CommandLine = tostring(EventData.CommandLine) 
  | summarize by BuildParentProcess=ParentProcessName, BuildProcess=Process, BuildAccount = Account, Computer, BuildCommand=CommandLine, timekey= bin(TimeGenerated, time_window), BuildProcessTime=TimeGenerated
  | join kind=inner(
  WindowsEvent
  | where TimeGenerated > ago(timeframe)
  // Look for file modifications to code file
  | where EventID == 4663 and EventData has_any ("0x6", "0x4", "0X100") and EventData has_any (".cs", ".cpp")
  | extend NewProcessName = tostring(EventData.NewProcessName)
  | extend Process=tostring(split(NewProcessName, '\\')[-1])
  | where Process !in (allow_list)
  // Look for code files, edit this to include file extensions used in build.
  | extend ObjectName = tostring(EventData.ObjectName)
  | where ObjectName endswith ".cs" or ObjectName endswith ".cpp"
  // 0x6 and 0x4 for file append, 0x100 for file replacements
  | extend AccessMask = tostring(EventData.AccessMask)  
  | where AccessMask == "0x6"  or AccessMask == "0x4" or AccessMask == "0X100"
  | extend ParentProcessName = tostring(EventData.ParentProcessName)
  | extend Account =  strcat(tostring(EventData.SubjectDomainName),"\\", tostring(EventData.SubjectUserName))
  | extend ProcessName = tostring(EventData.ProcessName)
  | summarize by FileEditParentProcess=ParentProcessName, FileEditAccount = Account, Computer, FileEdited=ObjectName, FileEditProcess=ProcessName, timekey= bin(TimeGenerated, time_window), FileEditTime=TimeGenerated)
  // join where build processes and file modifications seen at same time on same host
  on timekey, Computer
  // Limit to only where the file edit happens after the build process starts
  | where BuildProcessTime <= FileEditTime
  | summarize make_set(FileEdited), make_set(FileEditProcess), make_set(FileEditAccount) by timekey, Computer, BuildParentProcess, BuildProcess
  ))
  | extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
  | extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
  | project-away DomainIndex  
name: Potential Build Process Compromise
entityMappings:
- fieldMappings:
  - columnName: Computer
    identifier: FullName
  - columnName: HostName
    identifier: HostName
  - columnName: HostNameDomain
    identifier: DnsDomain
  entityType: Host
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/SecurityEvent/PotentialBuildProcessCompromise.yaml
tags:
- Solorigate
- NOBELIUM
requiredDataConnectors:
- connectorId: SecurityEvents
  dataTypes:
  - SecurityEvent
- connectorId: WindowsSecurityEvents
  dataTypes:
  - SecurityEvent
- connectorId: WindowsSecurityEvents
  dataTypes:
  - SecurityEvents
- connectorId: WindowsForwardedEvents
  dataTypes:
  - WindowsEvent
description: |
  'The query looks for source code files being modified immediately after a build process is started. The purpose of this is to look for malicious code injection during the build process.
  More details: https://techcommunity.microsoft.com/t5/azure-sentinel/monitoring-the-software-supply-chain-with-azure-sentinel/ba-p/2176463'  
kind: Scheduled
version: 1.1.4
metadata:
  author:
    name: Microsoft Security Research
  categories:
    domains:
    - Security - Others
  support:
    tier: Community
  source:
    kind: Community
queryFrequency: 1d
severity: Medium
relevantTechniques:
- T1554
triggerOperator: gt
triggerThreshold: 0
tactics:
- Persistence
id: 5ef06767-b37c-4818-b035-47de950d0046