Find sigma rule
Attack: Inhibit System Recovery
Adversaries may delete or remove built-in data and turn off services designed to aid in the recovery of a corrupted system to prevent recovery.(Citation: Talos Olympic Destroyer 2018)(Citation: FireEye WannaCry 2017) This may deny access to available backups and recovery options.
Operating systems may contain features that can help fix corrupted systems, such as a backup catalog, volume shadow copies, and automatic repair features. Adversaries may disable or delete system recovery features to augment the effects of Data Destruction and Data Encrypted for Impact.(Citation: Talos Olympic Destroyer 2018)(Citation: FireEye WannaCry 2017) Furthermore, adversaries may disable recovery notifications, then corrupt backups.(Citation: disable_notif_synology_ransom)
A number of native Windows utilities have been used by adversaries to disable or delete system recovery features:
-
vssadmin.exe
can be used to delete all volume shadow copies on a system -vssadmin.exe delete shadows /all /quiet
-
Windows Management Instrumentation can be used to delete volume shadow copies -
wmic shadowcopy delete
-
wbadmin.exe
can be used to delete the Windows Backup Catalog -wbadmin.exe delete catalog -quiet
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bcdedit.exe
can be used to disable automatic Windows recovery features by modifying boot configuration data -bcdedit.exe /set {default} bootstatuspolicy ignoreallfailures & bcdedit /set {default} recoveryenabled no
-
REAgentC.exe
can be used to disable Windows Recovery Environment (WinRE) repair/recovery options of an infected system -
diskshadow.exe
can be used to delete all volume shadow copies on a system -diskshadow delete shadows all
(Citation: Diskshadow) (Citation: Crytox Ransomware)
On network devices, adversaries may leverage Disk Wipe to delete backup firmware images and reformat the file system, then System Shutdown/Reboot to reload the device. Together this activity may leave network devices completely inoperable and inhibit recovery operations.
Adversaries may also delete “online” backups that are connected to their network – whether via network storage media or through folders that sync to cloud services.(Citation: ZDNet Ransomware Backups 2020) In cloud environments, adversaries may disable versioning and backup policies and delete snapshots, machine images, and prior versions of objects designed to be used in disaster recovery scenarios.(Citation: Dark Reading Code Spaces Cyber Attack)(Citation: Rhino Security Labs AWS S3 Ransomware)
MITRE
Tactic
- impact
technique
- T1490
Test : Modify VSS Service Permissions
OS
- windows
Description:
This atomic test alters the security settings of the Volume Shadow Copy Service (VSS) by modifying its permissions, potentially impacting system recovery operations. The specific permissions set by the command are as follows:
- Deny Generic All (GA) permissions to Network Users (NU)
- Deny GA permissions to Everyone (WD)
- Deny GA permissions to Anonymous (AN)
- Allow Full Access (FA) and Generic All (GA) permissions to Everyone (WD) in System ACL (SACL)
- Allow Object Inherit and Inherit Only (OIIO) Full Access (FA) and GA permissions to Everyone (WD) in SACL These permissions can significantly restrict VSS functionalities, including backup and restore operations. As such, it is essential to run this test only in a controlled environment with administrative privileges. A cleanup command is provided to reset VSS permissions to a common default configuration, which should be verified against your specific system’s configuration. It’s crucial to use this cleanup command after testing to ensure the system’s backup and recovery capabilities remain functional. Running this test on a production system or critical environment is not recommended without proper precautions and a robust recovery plan.
Executor
command_prompt