Tamper With Sophos AV Registry Keys

Hunt Hypothesis

Detects tamper attempts to sophos av functionality via registry key modification

Detection Rule

Sigma (Original)

title: Tamper With Sophos AV Registry Keys
id: 9f4662ac-17ca-43aa-8f12-5d7b989d0101
status: test
description: Detects tamper attempts to sophos av functionality via registry key modification
references:
    - https://redacted.com/blog/bianlian-ransomware-gang-gives-it-a-go/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-09-02
modified: 2023-08-17
tags:
    - attack.defense-impairment
    - attack.t1685
logsource:
    category: registry_set
    product: windows
detection:
    selection:
        TargetObject|contains:
            - '\Sophos Endpoint Defense\TamperProtection\Config\SAVEnabled'
            - '\Sophos Endpoint Defense\TamperProtection\Config\SEDEnabled'
            - '\Sophos\SAVService\TamperProtection\Enabled'
        Details: DWORD (0x00000000)
    condition: selection
falsepositives:
    - Some FP may occur when the feature is disabled by the AV itself, you should always investigate if the action was legitimate
level: high

KQL (Azure Sentinel)

imRegistry
| where (RegistryKey contains "\\Sophos Endpoint Defense\\TamperProtection\\Config\\SAVEnabled" or RegistryKey contains "\\Sophos Endpoint Defense\\TamperProtection\\Config\\SEDEnabled" or RegistryKey contains "\\Sophos\\SAVService\\TamperProtection\\Enabled") and RegistryValueData =~ "DWORD (0x00000000)"

KQL (Microsoft 365 Defender)

DeviceRegistryEvents
| where (RegistryKey contains "\\Sophos Endpoint Defense\\TamperProtection\\Config\\SAVEnabled" or RegistryKey contains "\\Sophos Endpoint Defense\\TamperProtection\\Config\\SEDEnabled" or RegistryKey contains "\\Sophos\\SAVService\\TamperProtection\\Enabled") and RegistryValueData =~ "DWORD (0x00000000)"

Required Data Sources

False Positive Guidance

• Some FP may occur when the feature is disabled by the AV itself, you should always investigate if the action was legitimate

MITRE ATT&CK Context

• Technique: T1685 — T1685

References

• https://redacted.com/blog/bianlian-ransomware-gang-gives-it-a-go/
• SigmaHQ Rule