HackTool - RemoteKrbRelay Execution

Status: test
Severity: high
Log source: product windows, category process_creation
Author: Nasreddine Bencherchali (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects the use of RemoteKrbRelay, a Kerberos relaying tool via CommandLine flags and PE metadata.

MITRE ATT&CK coverage

Tactic	Techniques
Credential Access	`T1558.003` Steal or Forge Kerberos Tickets: Kerberoasting

Event coverage

Provider	Event	Title
Sysmon	Event ID 1	Process creation

Rule body yaml

title: HackTool - RemoteKrbRelay Execution
id: a7664b14-75fb-4a50-a223-cb9bc0afbacf
status: test
description: |
    Detects the use of RemoteKrbRelay, a Kerberos relaying tool via CommandLine flags and PE metadata.
references:
    - https://github.com/CICADA8-Research/RemoteKrbRelay
author: Nasreddine Bencherchali (Nextron Systems)
date: 2024-06-27
tags:
    - attack.credential-access
    - attack.t1558.003
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\RemoteKrbRelay.exe'
        - OriginalFileName: 'RemoteKrbRelay.exe'
    selection_cli_required:
        CommandLine|contains|all:
            - ' -clsid '
            - ' -target '
            - ' -victim '
    # selection_cli_attacks:
    #     # Note: In the current implementation these flags do not require any other flags. Which means they can't be used on their own. They're already covered by "selection_cli_required"
    #     CommandLine|contains:
    #         - '-adcs ' # relay to HTTP Web Enrollment and get certificate
    #         - '-laps ' # relay to LDAP and extract LAPS passwords
    #         - '-ldapwhoami ' # relay to LDAP and get info about relayed user
    #         - '-shadowcred ' # relay to LDAP and setup Shadow Credentials
    selection_cli_attack_smb:
        CommandLine|contains|all:
            - '-smb ' # relay to SMB
            - '--smbkeyword '
        CommandLine|contains:
            - 'interactive'
            - 'secrets'
            - 'service-add'
    selection_cli_attack_rbcd_main:
        CommandLine|contains: '-rbcd ' # relay to LDAP and setup RBCD
    selection_cli_attack_rbcd_options:
        CommandLine|contains:
            - '-cn ' # Computer name that will be written to msDs-AllowedToActOnBehalfOfOtherIdentity
            - '--computername ' # Computer name that will be written to msDs-AllowedToActOnBehalfOfOtherIdentity
    selection_cli_attack_changepass:
        CommandLine|contains: '-chp ' # relay to LDAP and change user password
        CommandLine|contains|all:
            - '-chpPass ' # new password
            - '-chpUser ' # the name of the user whose password you want to change
    selection_cli_attack_addgrpname:
        CommandLine|contains|all:
            - '-addgroupmember ' # relay to LDAP and add user to group
            - '-group '
            - '-groupuser '
    condition: selection_img or selection_cli_required or all of selection_cli_attack_rbcd_* or selection_cli_attack_changepass or selection_cli_attack_addgrpname or selection_cli_attack_smb
falsepositives:
    - Unlikely
level: high

Stages and Predicates

Stage 0: `condition`

selection_img or selection_cli_required or all of selection_cli_attack_rbcd_* or selection_cli_attack_changepass or selection_cli_attack_addgrpname or selection_cli_attack_smb

Stage 1: `selection_img`

selection_img:
    - Image|endswith: '\RemoteKrbRelay.exe'
    - OriginalFileName: 'RemoteKrbRelay.exe'

Stage 2: `selection_cli_required`

selection_cli_required:
    CommandLine|contains|all:
        - ' -clsid '
        - ' -target '
        - ' -victim '

Stage 3: `selection_cli_attack_rbcd_main`

selection_cli_attack_rbcd_main:
    CommandLine|contains: '-rbcd '

Stage 4: `selection_cli_attack_rbcd_options`

selection_cli_attack_rbcd_options:
    CommandLine|contains:
        - '-cn '
        - '--computername '

Stage 5: `selection_cli_attack_changepass`

selection_cli_attack_changepass:
    CommandLine|contains: '-chp '
    CommandLine|contains|all:
        - '-chpPass '
        - '-chpUser '

Stage 6: `selection_cli_attack_addgrpname`

selection_cli_attack_addgrpname:
    CommandLine|contains|all:
        - '-addgroupmember '
        - '-group '
        - '-groupuser '

Stage 7: `selection_cli_attack_smb`

selection_cli_attack_smb:
    CommandLine|contains|all:
        - '-smb '
        - '--smbkeyword '
    CommandLine|contains:
        - 'interactive'
        - 'secrets'
        - 'service-add'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`CommandLine`	match	`-clsid` corpus 2 (sigma 2) `-target` `-victim` `--computername` `--smbkeyword` `-addgroupmember` `-chp` `-chpPass` `-chpUser` `-cn` `-group` `-groupuser` `-rbcd` `-smb` `interactive` corpus 3 (sigma 3) `secrets` `service-add`
`Image`	ends_with	`\RemoteKrbRelay.exe`
`OriginalFileName`	eq	`RemoteKrbRelay.exe`

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)

HackTool - RemoteKrbRelay Execution

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection_img`

Stage 2: `selection_cli_required`

Stage 3: `selection_cli_attack_rbcd_main`

Stage 4: `selection_cli_attack_rbcd_options`

Stage 5: `selection_cli_attack_changepass`

Stage 6: `selection_cli_attack_addgrpname`

Stage 7: `selection_cli_attack_smb`

Indicators

Keyboard shortcuts

Search operators

HackTool - RemoteKrbRelay Execution

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection_img

Stage 2: selection_cli_required

Stage 3: selection_cli_attack_rbcd_main

Stage 4: selection_cli_attack_rbcd_options

Stage 5: selection_cli_attack_changepass

Stage 6: selection_cli_attack_addgrpname

Stage 7: selection_cli_attack_smb

Indicators

Stage 0: `condition`

Stage 1: `selection_img`

Stage 2: `selection_cli_required`

Stage 3: `selection_cli_attack_rbcd_main`

Stage 4: `selection_cli_attack_rbcd_options`

Stage 5: `selection_cli_attack_changepass`

Stage 6: `selection_cli_attack_addgrpname`

Stage 7: `selection_cli_attack_smb`