VMMap Unsigned Dbghelp.DLL Potential Sideloading

Severity: high
Author: Nasreddine Bencherchali (Nextron Systems)
Source: upstream

Detects potential DLL sideloading of an unsigned dbghelp.dll by the Sysinternals VMMap.

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1574.001` Hijack Execution Flow: DLL
Privilege Escalation	`T1574.001` Hijack Execution Flow: DLL
Defense Evasion	`T1574.001` Hijack Execution Flow: DLL

Event coverage

Provider	Event ID	Title
Sysmon	7	Image loaded

Stages and Predicates

Stage 1: `selection`

or:
Image|endswith: '\vmmap.exe'
Image|endswith: '\vmmap64.exe'
ImageLoaded|contains: 'C:\Debuggers\dbghelp.dll'

Stage 2: `not 1 of filter_main_signed`

Signed: true

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	`\vmmap.exe` corpus 3 (sigma 3) `\vmmap64.exe` corpus 3 (sigma 3)
`ImageLoaded`	match	`C:\Debuggers\dbghelp.dll` corpus 2 (sigma 2)
`Signed`	eq	`true` corpus 8 (sigma 8)

Neighbors

Stricter alternatives (narrower than this rule)

The rules below may be useful if you find the current rule is too noisy / lacks specificity.

VMMap Signed Dbghelp.DLL Potential Sideloading [sigma] (adds 1 filter) (first-stage match only; downstream stages may differ)