Detection rules › Sigma

Suspicious Unsigned Thor Scanner Execution

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

Detects loading and execution of an unsigned thor scanner binary.

MITRE ATT&CK coverage

Event coverage

ProviderEventTitle
SysmonEvent ID 7Image loaded

Rule body yaml

title: Suspicious Unsigned Thor Scanner Execution
id: ea5c131b-380d-49f9-aeb3-920694da4d4b
status: stable
description: Detects loading and execution of an unsigned thor scanner binary.
references:
    - Internal Research
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-10-29
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.execution
    - attack.stealth
    - attack.t1574.001
logsource:
    category: image_load
    product: windows
detection:
    selection:
        Image|endswith:
            - '\thor.exe'
            - '\thor64.exe'
        ImageLoaded|endswith:
            - '\thor.exe'
            - '\thor64.exe'
    filter_main:
        Signed: 'true'
        SignatureStatus: 'valid'
        Signature: 'Nextron Systems GmbH'
    condition: selection and not filter_main
falsepositives:
    - Other legitimate binaries named "thor.exe" that aren't published by Nextron Systems
level: high

Stages and Predicates

Stage 0: condition

selection and not filter_main

Stage 1: selection

selection:
    Image|endswith:
        - '\thor.exe'
        - '\thor64.exe'
    ImageLoaded|endswith:
        - '\thor.exe'
        - '\thor64.exe'

Stage 2: not filter_main

filter_main:
    Signed: 'true'
    SignatureStatus: 'valid'
    Signature: 'Nextron Systems GmbH'

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

FieldKindExcluded values
SignatureeqNextron Systems GmbH
SignatureStatuseqvalid
Signedeqtrue

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.

FieldKindValues
Imageends_with
  • \thor.exe
  • \thor64.exe
ImageLoadedends_with
  • \thor.exe
  • \thor64.exe