Sofacy Trojan Loader Activity

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

Detects Trojan loader activity as used by APT28

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059.003` Command and Scripting Interpreter: Windows Command Shell
Stealth	`T1218.011` System Binary Proxy Execution: Rundll32

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation
Security-Auditing	Event ID 4688: A new process has been created.

Rule body

title: Sofacy Trojan Loader Activity
id: ba778144-5e3d-40cf-8af9-e28fb1df1e20
status: test
description: Detects Trojan loader activity as used by APT28
references:
    - https://researchcenter.paloaltonetworks.com/2018/02/unit42-sofacy-attacks-multiple-government-entities/
    - https://www.hybrid-analysis.com/sample/ff808d0a12676bfac88fd26f955154f8884f2bb7c534b9936510fd6296c543e8?environmentId=110
    - https://twitter.com/ClearskySec/status/960924755355369472
author: Florian Roth (Nextron Systems), Jonhnathan Ribeiro, oscd.community
date: 2018-03-01
modified: 2023-05-31
tags:
    - attack.execution
    - attack.stealth
    - attack.g0007
    - attack.t1059.003
    - attack.t1218.011
    - car.2013-10-002
    - detection.emerging-threats
logsource:
    category: process_creation
    product: windows
detection:
    selection_path:
        Image|endswith: '\rundll32.exe'
        CommandLine|contains:
            - '%LOCALAPPDATA%'
            - '\AppData\Local\'
    selection_extensions:
        - CommandLine|contains: '.dat",'
        - CommandLine|endswith:
              - '.dll #1'
              - '.dll" #1'
              - '.dll",#1'
    filter_main_exclude_temp:
        CommandLine|contains: '\AppData\Local\Temp\'
    condition: all of selection_* and not 1 of filter_main_*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

all of selection_* and not 1 of filter_main_*

Stage 1: `selection_path`

selection_path:
    Image|endswith: '\rundll32.exe'
    CommandLine|contains:
        - '%LOCALAPPDATA%'
        - '\AppData\Local\'

Stage 2: `selection_extensions`

selection_extensions:
    - CommandLine|contains: '.dat",'
    - CommandLine|endswith:
          - '.dll #1'
          - '.dll" #1'
          - '.dll",#1'

Stage 3: `not filter_main_exclude_temp`

filter_main_exclude_temp:
    CommandLine|contains: '\AppData\Local\Temp\'

Exclusions

The rule actively suppresses these predicates.

Field	Kind	Excluded values	Search
`CommandLine`	match	`\AppData\Local\Temp\`	`excludes:CommandLine` `field:"CommandLine" value:"\AppData\Local\Temp\"`

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	ends_with	`.dll #1` `.dll" #1` `.dll",#1`	`field:"CommandLine" kind:ends_with`
`CommandLine`	match	`%LOCALAPPDATA%` corpus 4 (sigma 4) `.dat",` `\AppData\Local\` corpus 11 (sigma 10, elastic 1)	`field:"CommandLine" kind:match`
`Image`	ends_with	`\rundll32.exe` corpus 94 (sigma 94)	`field:"Image" kind:ends_with value:"\rundll32.exe"`

Sofacy Trojan Loader Activity

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection_path

Stage 2: selection_extensions

Stage 3: not filter_main_exclude_temp

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection_path`

Stage 2: `selection_extensions`

Stage 3: `not filter_main_exclude_temp`