User agent search for log4j exploitation attempt

id: 29283b22-a1c0-4d16-b0a9-3460b655a46a
name: User agent search for log4j exploitation attempt
description: |
  'This query uses various log sources having user agent data to look for log4j CVE-2021-44228 exploitation attempt based on user agent pattern.
  Log4j is an open-source Apache logging library that is used in many Java-based applications. The regex and the string matching look for the most common attacks. This might not be comprehensive to detect every possible user agent variation.
   Reference: https://msrc-blog.microsoft.com/2021/12/11/microsofts-response-to-cve-2021-44228-apache-log4j2/'
severity: High
status: Available
requiredDataConnectors:
  - connectorId: SquidProxy
    dataTypes:
      - SquidProxy_CL
  - connectorId: Zscaler
    dataTypes:
      - CommonSecurityLog
  - connectorId: WAF
    dataTypes:
      - AzureDiagnostics
  - connectorId: Office365
    dataTypes:
      - OfficeActivity
  - connectorId: AzureActiveDirectory
    dataTypes:
      - SigninLogs
  - connectorId: AzureActiveDirectory
    dataTypes:
      - AADNonInteractiveUserSignInLogs
  - connectorId: AWS
    dataTypes:
      - AWSCloudTrail
  - connectorId: AzureMonitor(IIS)
    dataTypes:
      - W3CIISLog
queryFrequency: 1d
queryPeriod: 1d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - InitialAccess
relevantTechniques:
  - T1190
tags:
    - log4j
    - log4shell
    - CVE2021-44228
    - Schema: ASimWebSession
    - SchemaVersion: 0.2.1
    - Schema: ASimNetworkSessions
    - SchemaVersion: 0.2.1
query: |
  let UserAgentString = dynamic (["${jndi:ldap:/", "${jndi:rmi:/", "${jndi:ldaps:/", "${jndi:dns:/", "${jndi:iiop:/","${jndi:","${jndi:nds:/","${jndi:corba/"]);
  let UARegexMinimalString=dynamic(['{','%7b', '%7B']);
  let UARegex = @'(\\$|%24)(\\{|%7B)([^jJ]*[jJ])([^nN]*[nN])([^dD]*[dD])([^iI]*[iI])(:|%3A|\\$|%24|}|%7D)';
  (union isfuzzy=true
  (OfficeActivity
  | where UserAgent has_any (UserAgentString) or UserAgent matches regex UARegex
  | summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent, SourceIP = ClientIP, Account = UserId, Type, Operation
  ),
  (AzureDiagnostics
  | where Category in ("FrontdoorWebApplicationFirewallLog", "FrontdoorAccessLog", "ApplicationGatewayFirewallLog", "ApplicationGatewayAccessLog")
  | where userAgent_s has_any (UserAgentString) or userAgent_s matches regex UARegex
  | summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent = userAgent_s, SourceIP = column_ifexists("clientIp_s",clientIP_s), Type, column_ifexists("originalHost_s",host_s), Url = requestUri_s, HttpStatus = column_ifexists("httpStatusDetails_s",httpStatus_d), column_ifexists("trackingReference_s",transactionId_g), ruleName_s, ResourceType, ResourceId
  ),
  (
  W3CIISLog
  | where csUserAgent has_any (UserAgentString) or csUserAgent matches regex UARegex
  | summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent = csUserAgent, SourceIP = cIP, Account = csUserName, Type, sSiteName, csMethod, Url = csUriStem
  ),
  (
  AWSCloudTrail
  | where UserAgent has_any (UserAgentString) or UserAgent matches regex UARegex
  | summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent, SourceIP = SourceIpAddress, Account = UserIdentityUserName, Type, EventName
  ),
  (SigninLogs
  | where UserAgent has_any (UserAgentString) or UserAgent matches regex UARegex
  | summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent, SourceIP = IPAddress, Account = UserPrincipalName, Type, Operation = OperationName, tostring(LocationDetails), tostring(DeviceDetail),    AppDisplayName, ClientAppUsed
  ),
  (AADNonInteractiveUserSignInLogs 
  | where UserAgent has_any (UserAgentString) or UserAgent matches regex UARegex
  | summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by UserAgent, SourceIP = IPAddress, Account = UserPrincipalName, Type, Operation = OperationName, tostring(LocationDetails), tostring(DeviceDetail), AppDisplayName, ClientAppUsed
  ),
  (_Im_WebSession (httpuseragent_has_any=array_concat(UserAgentString,UARegexMinimalString))
  | where HttpUserAgent has_any (UserAgentString) or HttpUserAgent matches regex UARegex
  | summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by HttpUserAgent, SourceIP = SrcIpAddr, DstIpAddr, Account = SrcUsername, Url, Type
  )
  )
entityMappings:
  - entityType: URL
    fieldMappings:
      - identifier: Url
        columnName: Url
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: SourceIP
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: Account
version: 1.0.9
kind: Scheduled