Load Of RstrtMgr.DLL By An Uncommon Process

Severity: low
Author: Luc Génaux
Source: upstream

Detects the load of RstrtMgr DLL (Restart Manager) by an uncommon process. This library has been used during ransomware campaigns to kill processes that would prevent file encryption by locking them (e.g. Conti ransomware, Cactus ransomware). It has also recently been seen used by the BiBi wiper for Windows. It could also be used for anti-analysis purposes by shut downing specific processes.

MITRE ATT&CK coverage

Tactic	Techniques
Defense Evasion	`T1562.001` Impair Defenses: Disable or Modify Tools
Impact	`T1486` Data Encrypted for Impact

Event coverage

Provider	Event ID	Title
Sysmon	7	Image loaded

Stages and Predicates

Stage 1: `selection`

or:
ImageLoaded|endswith: '\RstrtMgr.dll'
OriginalFileName: RstrtMgr.dll

Stage 2: `not 1 of filter_main_*`

or:
Image|endswith: .tmp
Image|contains: '.tmp\'
Image|contains: '\AppData\Local\Temp\is-'
Image|startswith: 'C:\Users\'''
Image|startswith: 'C:\$WINDOWS.~BT\'''
Image|startswith: 'C:\$WinREAgent\'''
Image|startswith: 'C:\Program Files (x86)\'''
Image|startswith: 'C:\Program Files\'''
Image|startswith: 'C:\ProgramData\'''
Image|startswith: 'C:\WUDownloadCache\'''
Image|startswith: 'C:\Windows\SoftwareDistribution\'''
Image|startswith: 'C:\Windows\SysNative\'''
Image|startswith: 'C:\Windows\SysWOW64\'''
Image|startswith: 'C:\Windows\System32\'''
Image|startswith: 'C:\Windows\Temp\'''
Image|startswith: 'C:\Windows\WinSxS\'''
Image|startswith: 'C:\Windows\explorer.exe'''

Stage 3: `not 1 of filter_optional_onedrive`

Image|endswith: '\AppData\Local\Microsoft\OneDrive\OneDriveStandaloneUpdater.exe'
Image|startswith: 'C:\Users\'

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.

Field	Kind	Values
`Image`	ends_with	`.tmp` corpus 2 (sigma 2) `\AppData\Local\Microsoft\OneDrive\OneDriveStandaloneUpdater.exe`
`Image`	match	`.tmp\` `\AppData\Local\Temp\is-`
`Image`	starts_with	`C:\$WINDOWS.~BT\'` `C:\$WinREAgent\'` `C:\Program Files (x86)\'` `C:\Program Files\'` `C:\ProgramData\'` `C:\Users\` corpus 7 (sigma 7) `C:\Users\'` corpus 2 (sigma 2) `C:\WUDownloadCache\'` `C:\Windows\SoftwareDistribution\'` `C:\Windows\SysNative\'` `C:\Windows\SysWOW64\'` `C:\Windows\System32\'` `C:\Windows\Temp\'` `C:\Windows\WinSxS\'` `C:\Windows\explorer.exe'`
`ImageLoaded`	ends_with	`\RstrtMgr.dll` corpus 2 (sigma 2)
`OriginalFileName`	eq	`RstrtMgr.dll` corpus 2 (sigma 2)