Suspicious Connection to Remote Account

Status: test
Severity: low
Log source: category ps_script, product windows
Author: frack113
Source: github.com/SigmaHQ/sigma

Adversaries with no prior knowledge of legitimate credentials within the system or environment may guess passwords to attempt access to accounts. Without knowledge of the password for an account, an adversary may opt to systematically guess the password using a repetitive or iterative mechanism

MITRE ATT&CK coverage

Tactic	Techniques
Credential Access	`T1110.001` Brute Force: Password Guessing

Telemetry coverage

Provider	Record / event type
PowerShell	Event ID 4104: Creating Scriptblock text (MessageNumber of MessageTotal).

Rule body

title: Suspicious Connection to Remote Account
id: 1883444f-084b-419b-ac62-e0d0c5b3693f
status: test
description: |
    Adversaries with no prior knowledge of legitimate credentials within the system or environment may guess passwords to attempt access to accounts.
    Without knowledge of the password for an account, an adversary may opt to systematically guess the password using a repetitive or iterative mechanism
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1110.001/T1110.001.md#atomic-test-2---brute-force-credentials-of-single-active-directory-domain-user-via-ldap-against-domain-controller-ntlm-or-kerberos
author: frack113
date: 2021-12-27
tags:
    - attack.credential-access
    - attack.t1110.001
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection:
        ScriptBlockText|contains:
            - 'System.DirectoryServices.Protocols.LdapDirectoryIdentifier'
            - 'System.Net.NetworkCredential'
            - 'System.DirectoryServices.Protocols.LdapConnection'
    condition: selection
falsepositives:
    - Unknown
level: low

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    ScriptBlockText|contains:
        - 'System.DirectoryServices.Protocols.LdapDirectoryIdentifier'
        - 'System.Net.NetworkCredential'
        - 'System.DirectoryServices.Protocols.LdapConnection'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`ScriptBlockText`	match	`System.DirectoryServices.Protocols.LdapConnection` `System.DirectoryServices.Protocols.LdapDirectoryIdentifier` `System.Net.NetworkCredential`	`field:"ScriptBlockText" kind:match`