Suspicious Key Manager Access

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

Detects the invocation of the Stored User Names and Passwords dialogue (Key Manager)

Known false positives

Administrative activity

MITRE ATT&CK coverage

Tactic	Techniques
Credential Access	`T1555.004` Credentials from Password Stores: Windows Credential Manager

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation

Rule body

title: Suspicious Key Manager Access
id: a4694263-59a8-4608-a3a0-6f8d3a51664c
status: test
description: Detects the invocation of the Stored User Names and Passwords dialogue (Key Manager)
references:
    - https://twitter.com/NinjaParanoid/status/1516442028963659777
author: Florian Roth (Nextron Systems)
date: 2022-04-21
modified: 2023-02-09
tags:
    - attack.credential-access
    - attack.t1555.004
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\rundll32.exe'
        - OriginalFileName: 'RUNDLL32.EXE'
    selection_cli:
        CommandLine|contains|all:
            - 'keymgr'
            - 'KRShowKeyMgr'
    condition: all of selection_*
falsepositives:
    - Administrative activity
level: high

Stages and Predicates

Stage 0: `condition`

all of selection_*

Stage 1: `selection_img`

selection_img:
    - Image|endswith: '\rundll32.exe'
    - OriginalFileName: 'RUNDLL32.EXE'

Stage 2: `selection_cli`

selection_cli:
    CommandLine|contains|all:
        - 'keymgr'
        - 'KRShowKeyMgr'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`KRShowKeyMgr` `keymgr`	`field:"CommandLine" kind:match`
`Image`	ends_with	`\rundll32.exe` corpus 94 (sigma 94)	`field:"Image" kind:ends_with value:"\rundll32.exe"`
`OriginalFileName`	eq	`RUNDLL32.EXE` corpus 78 (sigma 35, elastic 22, splunk 21)	`field:"OriginalFileName" kind:eq value:"RUNDLL32.EXE"`

Suspicious Key Manager Access

Known false positives

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection_img

Stage 2: selection_cli

Indicators

Stage 0: `condition`

Stage 1: `selection_img`

Stage 2: `selection_cli`