Potential Process Hollowing Activity

Severity: medium
Author: Christopher Peacock '@securepeacock', SCYTHE '@scythe_io', Sittikorn S
Source: upstream

Detects when a memory process image does not match the disk image, indicative of process hollowing.

MITRE ATT&CK coverage

Tactic	Techniques
Privilege Escalation	`T1055.012` Process Injection: Process Hollowing
Defense Evasion	`T1055.012` Process Injection: Process Hollowing

Event coverage

Provider	Event ID	Title
Sysmon	25	ProcessTampering (Process image change)

Stages and Predicates

Stage 1: `selection`

Type: 'Image is replaced'

Stage 2: `not 1 of filter_main_generic`

or:
Image|contains: ':\Program Files (x86)'
Image|contains: ':\Program Files\'
Image|contains: ':\Windows\SysWOW64\wbem\WMIADAP.exe'
Image|contains: ':\Windows\System32\wbem\WMIADAP.exe'

Stage 3: `not 1 of filter_optional_*`

or:
Image|endswith: '\opera.exe'
Image|contains: '\AppData\Local\Programs\Opera\'
Image|endswith: '\WindowsApps\MicrosoftEdge.exe'

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	`\WindowsApps\MicrosoftEdge.exe` corpus 12 (sigma 12) `\opera.exe` corpus 21 (sigma 21)
`Image`	match	`:\Program Files (x86)` `:\Program Files\` corpus 6 (sigma 6) `:\Windows\SysWOW64\wbem\WMIADAP.exe` `:\Windows\System32\wbem\WMIADAP.exe` `\AppData\Local\Programs\Opera\` corpus 5 (sigma 5)
`Type`	eq	`Image is replaced`