CYFIRMA - Attack Surface - Weak Certificate Exposure - Medium Rule

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Id	5a617ff2-3e3d-44e7-b761-9f0d542ae191
Rulename	CYFIRMA - Attack Surface - Weak Certificate Exposure - Medium Rule
Description	This alert indicates that a weak or insecure SSL/TLS certificate has been detected on a public-facing asset monitored by Cyfirma. Such certificates do not meet modern encryption standards and are considered insecure, especially for handling sensitive transactions. This exposure increases the risk of man-in-the-middle attacks and loss of data integrity or confidentiality. Immediate remediation is advised by replacing weak certificates with strong, industry-compliant ones.
Severity	Medium
Tactics	DefenseEvasion ResourceDevelopment Reconnaissance InitialAccess CredentialAccess
Techniques	T1553 T1588 T1595 T1190 T1552
Required data connectors	CyfirmaAttackSurfaceAlertsConnector
Kind	Scheduled
Query frequency	5m
Query period	5m
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Cyfirma Attack Surface/Analytic Rules/ASCertificatesMediumRule.yaml
Version	1.0.1
Arm template	5a617ff2-3e3d-44e7-b761-9f0d542ae191.json

KQL

// Medium Severity Weak Certificate Exposure Detected
let timeFrame = 5m;
CyfirmaASCertificatesAlerts_CL
| where severity == 'High' and TimeGenerated between (ago(timeFrame) .. now())
| extend
    Description=description,
    FirstSeen=first_seen,
    LastSeen=last_seen,
    ValidFrom=valid_from,
    ValidTo=valid_to,
    RiskScore=risk_score,
    Domain=sub_domain,
    TopDomain=top_domain,
    Protocols=protocols,
    SelfSigned=self_signed,
    AlertUID=alert_uid,
    UID=uid,
    CertificateData= cert_data,
    CertificateHash=cert_hash,
    IssuedBy=issued_by,
    IssuedTo=issued_to,
    ProviderName='CYFIRMA',
    ProductName='DeCYFIR/DeTCT'
| project
    TimeGenerated,
    Description,
    Domain,
    TopDomain,
    RiskScore,
    FirstSeen,
    LastSeen,
    ValidFrom,
    ValidTo,
    Protocols,
    SelfSigned,
    CertificateData,
    CertificateHash,
    IssuedBy,
    IssuedTo,
    ProviderName,
    ProductName

YAML

queryPeriod: 5m
query: |
  // Medium Severity Weak Certificate Exposure Detected
  let timeFrame = 5m;
  CyfirmaASCertificatesAlerts_CL
  | where severity == 'High' and TimeGenerated between (ago(timeFrame) .. now())
  | extend
      Description=description,
      FirstSeen=first_seen,
      LastSeen=last_seen,
      ValidFrom=valid_from,
      ValidTo=valid_to,
      RiskScore=risk_score,
      Domain=sub_domain,
      TopDomain=top_domain,
      Protocols=protocols,
      SelfSigned=self_signed,
      AlertUID=alert_uid,
      UID=uid,
      CertificateData= cert_data,
      CertificateHash=cert_hash,
      IssuedBy=issued_by,
      IssuedTo=issued_to,
      ProviderName='CYFIRMA',
      ProductName='DeCYFIR/DeTCT'
  | project
      TimeGenerated,
      Description,
      Domain,
      TopDomain,
      RiskScore,
      FirstSeen,
      LastSeen,
      ValidFrom,
      ValidTo,
      Protocols,
      SelfSigned,
      CertificateData,
      CertificateHash,
      IssuedBy,
      IssuedTo,
      ProviderName,
      ProductName  
incidentConfiguration:
  groupingConfiguration:
    lookbackDuration: PT5H
    reopenClosedIncident: false
    matchingMethod: AllEntities
    enabled: false
  createIncident: true
name: CYFIRMA - Attack Surface - Weak Certificate Exposure - Medium Rule
entityMappings:
- fieldMappings:
  - columnName: HostName
    identifier: DomainName
  entityType: DNS
- fieldMappings:
  - columnName: TopDomain
    identifier: HostName
  - columnName: Domain
    identifier: DnsDomain
  entityType: Host
queryFrequency: 5m
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Cyfirma Attack Surface/Analytic Rules/ASCertificatesMediumRule.yaml
alertDetailsOverride:
  alertDisplayNameFormat: CYFIRMA - Medium Severity Weak Certificate Exposure Detected for this Domain  - {{Domain}}
  alertDescriptionFormat: CYFIRMA - Medium Severity Weak Certificate Exposure Detected  - {{Description}}
  alertDynamicProperties:
  - value: ProductName
    alertProperty: ProductName
  - value: ProviderName
    alertProperty: ProviderName
description: |
  'This alert indicates that a weak or insecure SSL/TLS certificate has been detected on a public-facing asset monitored by Cyfirma. 
  Such certificates do not meet modern encryption standards and are considered insecure, especially for handling sensitive transactions. 
  This exposure increases the risk of man-in-the-middle attacks and loss of data integrity or confidentiality. 
  Immediate remediation is advised by replacing weak certificates with strong, industry-compliant ones.'  
kind: Scheduled
version: 1.0.1
eventGroupingSettings:
  aggregationKind: AlertPerResult
status: Available
severity: Medium
requiredDataConnectors:
- connectorId: CyfirmaAttackSurfaceAlertsConnector
  dataTypes:
  - CyfirmaASCertificatesAlerts_CL
triggerOperator: gt
triggerThreshold: 0
customDetails:
  IssuedTo: IssuedTo
  TimeGenerated: TimeGenerated
  ValidFrom: ValidFrom
  IssuedBy: IssuedBy
  ValidTo: ValidTo
  LastSeen: LastSeen
  Domain: Domain
  Description: Description
  CertificateData: CertificateData
  FirstSeen: FirstSeen
  CertificateHash: CertificateHash
  TopDomain: TopDomain
  SelfSigned: SelfSigned
  Protocols: Protocols
  RiskScore: RiskScore
tactics:
- DefenseEvasion
- ResourceDevelopment
- Reconnaissance
- InitialAccess
- CredentialAccess
id: 5a617ff2-3e3d-44e7-b761-9f0d542ae191
relevantTechniques:
- T1553
- T1588
- T1595
- T1190
- T1552

ARM