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Sigma detection rules

6 rules indexed · SIEM-agnostic detection content
Sigma is the open generic signature format for SIEM systems. Each rule below converts to native syntax for Splunk, Elastic, Sentinel, and other SIEMs. Expand any rule to see its raw YAML.
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Detection rules

6 shown of 6
high
Attempts of Kerberos Coercion Via DNS SPN Spoofing
Detects the presence of "UWhRC....AAYBAAAA" pattern in command line. The pattern "1UWhRCAAAAA..BAAAA" is a base64-encoded signature that corresponds to a marshaled CREDENTIAL_TARGET_INFORMATION structure. Attackers can use this technique to coerce authentication from victim systems to attacker-controlled hosts. It is one of the strong indicators of a Kerberos coercion attack, where adversaries manipulate DNS records to spoof Service Principal Names (SPNs) and redirect authentication requests like in CVE-2025-33073. If you see this pattern in the command line, it is likely an attempt to add spoofed Service Principal Names (SPNs) to DNS records, or checking for the presence of such records through the `nslookup` command.
status experimental author Swachchhanda Shrawan Poudel (Nextron Systems) id 0ed99dda-6a35-11ef-8c99-0242ac120002
view Sigma YAML 
title: Attempts of Kerberos Coercion Via DNS SPN Spoofing
id: 0ed99dda-6a35-11ef-8c99-0242ac120002
related:
    - id: b07e58cf-cacc-4135-8473-ccb2eba63dd2
      type: similar
status: experimental
description: |
    Detects the presence of "UWhRC....AAYBAAAA" pattern in command line.
    The pattern "1UWhRCAAAAA..BAAAA" is a base64-encoded signature that corresponds to a marshaled CREDENTIAL_TARGET_INFORMATION structure.
    Attackers can use this technique to coerce authentication from victim systems to attacker-controlled hosts.
    It is one of the strong indicators of a Kerberos coercion attack, where adversaries manipulate DNS records
    to spoof Service Principal Names (SPNs) and redirect authentication requests like in CVE-2025-33073.
    If you see this pattern in the command line, it is likely an attempt to add spoofed Service Principal Names (SPNs) to DNS records,
    or checking for the presence of such records through the `nslookup` command.
references:
    - https://www.synacktiv.com/publications/ntlm-reflection-is-dead-long-live-ntlm-reflection-an-in-depth-analysis-of-cve-2025
    - https://googleprojectzero.blogspot.com/2021/10/using-kerberos-for-authentication-relay.html
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-06-20
tags:
    - attack.collection
    - attack.credential-access
    - attack.persistence
    - attack.privilege-escalation
    - attack.t1557.001
    - attack.t1187
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|contains|all:
            - 'UWhRCA'
            - 'BAAAA'
    condition: selection
falsepositives:
    - Unknown
level: high
high
PetitPotam Suspicious Kerberos TGT Request
Detect suspicious Kerberos TGT requests. Once an attacer obtains a computer certificate by abusing Active Directory Certificate Services in combination with PetitPotam, the next step would be to leverage the certificate for malicious purposes. One way of doing this is to request a Kerberos Ticket Granting Ticket using a tool like Rubeus. This request will generate a 4768 event with some unusual fields depending on the environment. This analytic will require tuning, we recommend filtering Account_Name to the Domain Controller computer accounts.
status test author Mauricio Velazco, Michael Haag id 6a53d871-682d-40b6-83e0-b7c1a6c4e3a5
view Sigma YAML 
title: PetitPotam Suspicious Kerberos TGT Request
id: 6a53d871-682d-40b6-83e0-b7c1a6c4e3a5
status: test
description: |
    Detect suspicious Kerberos TGT requests.
    Once an attacer obtains a computer certificate by abusing Active Directory Certificate Services in combination with PetitPotam, the next step would be to leverage the certificate for malicious purposes.
    One way of doing this is to request a Kerberos Ticket Granting Ticket using a tool like Rubeus.
    This request will generate a 4768 event with some unusual fields depending on the environment.
    This analytic will require tuning, we recommend filtering Account_Name to the Domain Controller computer accounts.
references:
    - https://github.com/topotam/PetitPotam
    - https://isc.sans.edu/forums/diary/Active+Directory+Certificate+Services+ADCS+PKI+domain+admin+vulnerability/27668/
    - https://github.com/splunk/security_content/blob/88d689fe8a055d8284337b9fad5d9152b42043db/detections/endpoint/petitpotam_suspicious_kerberos_tgt_request.yml
author: Mauricio Velazco, Michael Haag
date: 2021-09-02
modified: 2022-10-05
tags:
    - attack.credential-access
    - attack.t1187
logsource:
    product: windows
    service: security
    definition: 'The advanced audit policy setting "Account Logon > Kerberos Authentication Service" must be configured for Success/Failure'
detection:
    selection:
        EventID: 4768
        TargetUserName|endswith: '$'
        CertThumbprint|contains: '*'
    filter_local:
        IpAddress: '::1'
    filter_thumbprint:
        CertThumbprint: ''
    condition: selection and not 1 of filter_*
falsepositives:
    - False positives are possible if the environment is using certificates for authentication. We recommend filtering Account_Name to the Domain Controller computer accounts.
level: high
high
Possible PetitPotam Coerce Authentication Attempt
Detect PetitPotam coerced authentication activity.
status test author Mauricio Velazco, Michael Haag id 1ce8c8a3-2723-48ed-8246-906ac91061a6
view Sigma YAML 
title: Possible PetitPotam Coerce Authentication Attempt
id: 1ce8c8a3-2723-48ed-8246-906ac91061a6
status: test
description: Detect PetitPotam coerced authentication activity.
references:
    - https://github.com/topotam/PetitPotam
    - https://github.com/splunk/security_content/blob/0dd6de32de2118b2818550df9e65255f4109a56d/detections/endpoint/petitpotam_network_share_access_request.yml
author: Mauricio Velazco, Michael Haag
date: 2021-09-02
modified: 2022-08-11
tags:
    - attack.credential-access
    - attack.t1187
logsource:
    product: windows
    service: security
    definition: 'The advanced audit policy setting "Object Access > Detailed File Share" must be configured for Success/Failure'
detection:
    selection:
        EventID: 5145
        ShareName|startswith: '\\\\' # looking for the string \\somethink\IPC$
        ShareName|endswith: '\IPC$'
        RelativeTargetName: lsarpc
        SubjectUserName: ANONYMOUS LOGON
    condition: selection
falsepositives:
    - Unknown. Feedback welcomed.
level: high
high
Suspicious DNS Query Indicating Kerberos Coercion via DNS Object SPN Spoofing
Detects DNS queries containing patterns associated with Kerberos coercion attacks via DNS object spoofing. The pattern "1UWhRCAAAAA..BAAAA" is a base64-encoded signature that corresponds to a marshaled CREDENTIAL_TARGET_INFORMATION structure. Attackers can use this technique to coerce authentication from victim systems to attacker-controlled hosts. It is one of the strong indicators of a Kerberos coercion attack, where adversaries manipulate DNS records to spoof Service Principal Names (SPNs) and redirect authentication requests like CVE-2025-33073.
status experimental author Swachchhanda Shrawan Poudel (Nextron Systems) id e7a21b5f-d8c4-4ae5-b8d9-93c5d3f28e1c
view Sigma YAML 
title: Suspicious DNS Query Indicating Kerberos Coercion via DNS Object SPN Spoofing
id: e7a21b5f-d8c4-4ae5-b8d9-93c5d3f28e1c
related:
    - id: b07e58cf-cacc-4135-8473-ccb2eba63dd2 # Potential Kerberos Coercion via DNS Object Spoofing
      type: similar
    - id: 5588576c-5898-4fac-bcdd-7475a60e8f43 # Suspicious DNS Query Indicating Kerberos Coercion via DNS Object Spoofing - Network
      type: similar
status: experimental
description: |
    Detects DNS queries containing patterns associated with Kerberos coercion attacks via DNS object spoofing.
    The pattern "1UWhRCAAAAA..BAAAA" is a base64-encoded signature that corresponds to a marshaled CREDENTIAL_TARGET_INFORMATION structure.
    Attackers can use this technique to coerce authentication from victim systems to attacker-controlled hosts.
    It is one of the strong indicators of a Kerberos coercion attack, where adversaries manipulate DNS records
    to spoof Service Principal Names (SPNs) and redirect authentication requests like CVE-2025-33073.
references:
    - https://www.synacktiv.com/publications/ntlm-reflection-is-dead-long-live-ntlm-reflection-an-in-depth-analysis-of-cve-2025
    - https://googleprojectzero.blogspot.com/2021/10/using-kerberos-for-authentication-relay.html
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-06-20
tags:
    - attack.collection
    - attack.credential-access
    - attack.persistence
    - attack.privilege-escalation
    - attack.t1557.001
    - attack.t1187
logsource:
    product: windows
    category: dns_query
detection:
    selection:
        QueryName|contains|all:
            - 'UWhRCA'
            - 'BAAAA'
    condition: selection
falsepositives:
    - Unknown
level: high
high
Suspicious DNS Query Indicating Kerberos Coercion via DNS Object SPN Spoofing - Network
Detects DNS queries containing patterns associated with Kerberos coercion attacks via DNS object spoofing. The pattern "1UWhRCAAAAA..BAAAA" is a base64-encoded signature that corresponds to a marshaled CREDENTIAL_TARGET_INFORMATION structure. Attackers can use this technique to coerce authentication from victim systems to attacker-controlled hosts. It is one of the strong indicators of a Kerberos coercion attack, where adversaries manipulate DNS records to spoof Service Principal Names (SPNs) and redirect authentication requests like CVE-2025-33073.
status experimental author Swachchhanda Shrawan Poudel (Nextron Systems) id 5588576c-5898-4fac-bcdd-7475a60e8f43
view Sigma YAML 
title: Suspicious DNS Query Indicating Kerberos Coercion via DNS Object SPN Spoofing - Network
id: 5588576c-5898-4fac-bcdd-7475a60e8f43
related:
    - id: b07e58cf-cacc-4135-8473-ccb2eba63dd2 # Potential Kerberos Coercion via DNS Object Spoofing
      type: similar
    - id: e7a21b5f-d8c4-4ae5-b8d9-93c5d3f28e1c # Suspicious DNS Query Indicating Kerberos Coercion via DNS Object Spoofing
      type: similar
status: experimental
description: |
    Detects DNS queries containing patterns associated with Kerberos coercion attacks via DNS object spoofing.
    The pattern "1UWhRCAAAAA..BAAAA" is a base64-encoded signature that corresponds to a marshaled CREDENTIAL_TARGET_INFORMATION structure.
    Attackers can use this technique to coerce authentication from victim systems to attacker-controlled hosts.
    It is one of the strong indicators of a Kerberos coercion attack, where adversaries manipulate DNS records
    to spoof Service Principal Names (SPNs) and redirect authentication requests like CVE-2025-33073.
references:
    - https://www.synacktiv.com/publications/ntlm-reflection-is-dead-long-live-ntlm-reflection-an-in-depth-analysis-of-cve-2025
    - https://googleprojectzero.blogspot.com/2021/10/using-kerberos-for-authentication-relay.html
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-06-20
tags:
    - attack.collection
    - attack.credential-access
    - attack.persistence
    - attack.privilege-escalation
    - attack.t1557.001
    - attack.t1187
logsource:
    product: zeek
    service: dns
detection:
    selection:
        query|contains|all:
            - 'UWhRCA' # Follows this pattern UWhRCAAAAA..BAAA
            - 'BAAAA'
    condition: selection
falsepositives:
    - Unknown
level: high
medium
Potential PetitPotam Attack Via EFS RPC Calls
Detects usage of the windows RPC library Encrypting File System Remote Protocol (MS-EFSRPC). Variations of this RPC are used within the attack refereed to as PetitPotam. The usage of this RPC function should be rare if ever used at all. Thus usage of this function is uncommon enough that any usage of this RPC function should warrant further investigation to determine if it is legitimate. View surrounding logs (within a few minutes before and after) from the Source IP to. Logs from from the Source IP would include dce_rpc, smb_mapping, smb_files, rdp, ntlm, kerberos, etc..'
status test author @neu5ron, @Antonlovesdnb, Mike Remen id 4096842a-8f9f-4d36-92b4-d0b2a62f9b2a
view Sigma YAML 
title: Potential PetitPotam Attack Via EFS RPC Calls
id: 4096842a-8f9f-4d36-92b4-d0b2a62f9b2a
status: test
description: |
    Detects usage of the windows RPC library Encrypting File System Remote Protocol (MS-EFSRPC). Variations of this RPC are used within the attack refereed to as PetitPotam.
    The usage of this RPC function should be rare if ever used at all.
    Thus usage of this function is uncommon enough that any usage of this RPC function should warrant further investigation to determine if it is legitimate.
     View surrounding logs (within a few minutes before and after) from the Source IP to. Logs from from the Source IP would include dce_rpc, smb_mapping, smb_files, rdp, ntlm, kerberos, etc..'
references:
    - https://github.com/topotam/PetitPotam/blob/d83ac8f2dd34654628c17490f99106eb128e7d1e/PetitPotam/PetitPotam.cpp
    - https://msrc.microsoft.com/update-guide/vulnerability/ADV210003
    - https://vx-underground.org/archive/Symantec/windows-vista-network-attack-07-en.pdf
    - https://threatpost.com/microsoft-petitpotam-poc/168163/
author: '@neu5ron, @Antonlovesdnb, Mike Remen'
date: 2021-08-17
modified: 2022-11-28
tags:
    - attack.collection
    - attack.credential-access
    - attack.t1557.001
    - attack.t1187
logsource:
    product: zeek
    service: dce_rpc
detection:
    selection:
        operation|startswith: 'efs'
    condition: selection
falsepositives:
    - Uncommon but legitimate windows administrator or software tasks that make use of the Encrypting File System RPC Calls. Verify if this is common activity (see description).
level: medium
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