Suspicious Process Access to LSASS with Dbgcore/Dbghelp DLLs

Severity: high
Author: Swachchhanda Shrawan Poudel (Nextron Systems)
Source: upstream

Detects suspicious process access to LSASS.exe from processes located in uncommon locations with dbgcore.dll or dbghelp.dll in the call trace. These DLLs contain functions like MiniDumpWriteDump that can be abused for credential dumping purposes. While modern tools like Mimikatz have moved to using ntdll.dll, dbgcore.dll and dbghelp.dll are still used by basic credential dumping utilities and legacy tools for LSASS memory access and process suspension techniques.

MITRE ATT&CK coverage

Tactic	Techniques
Defense Evasion	`T1562.001` Impair Defenses: Disable or Modify Tools
Credential Access	`T1003.001` OS Credential Dumping: LSASS Memory

Event coverage

Provider	Event ID	Title
Sysmon	10	ProcessAccess

Stages and Predicates

Stage 1: `all of selection_lsass_calltrace`

or:
CallTrace|contains: dbgcore.dll
CallTrace|contains: dbghelp.dll
TargetImage|endswith: '\lsass.exe'

Stage 2: `all of selection_susp_location`

or:
SourceImage|contains: ':\Perflogs\'
SourceImage|contains: ':\Temp\'
SourceImage|contains: ':\Users\Public\'
SourceImage|contains: '\$Recycle.Bin\'
SourceImage|contains: '\AppData\Roaming\'
SourceImage|contains: '\Contacts\'
SourceImage|contains: '\Desktop\'
SourceImage|contains: '\Documents\'
SourceImage|contains: '\Downloads\'
SourceImage|contains: '\Favorites\'
SourceImage|contains: '\Favourites\'
SourceImage|contains: '\Music\'
SourceImage|contains: '\Pictures\'
SourceImage|contains: '\Start Menu\Programs\Startup\'
SourceImage|contains: '\Users\Default\'
SourceImage|contains: '\Videos\'
SourceImage|contains: '\Windows\Temp\'
SourceImage|contains: '\inetpub\wwwroot\'

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
`CallTrace`	match	`dbgcore.dll` corpus 2 (sigma 2) `dbghelp.dll` corpus 2 (sigma 2)
`SourceImage`	match	`:\Perflogs\` corpus 7 (sigma 7) `:\Temp\` corpus 12 (sigma 12) `:\Users\Public\` corpus 14 (sigma 14) `\$Recycle.Bin\` corpus 2 (sigma 2) `\AppData\Roaming\` corpus 2 (sigma 2) `\Contacts\` corpus 5 (sigma 5) `\Desktop\` corpus 6 (sigma 6) `\Documents\` corpus 2 (sigma 2) `\Downloads\` corpus 8 (sigma 8) `\Favorites\` corpus 6 (sigma 6) `\Favourites\` corpus 5 (sigma 5) `\Music\` corpus 4 (sigma 4) `\Pictures\` corpus 5 (sigma 5) `\Start Menu\Programs\Startup\` corpus 2 (sigma 2) `\Users\Default\` corpus 4 (sigma 4) `\Videos\` corpus 4 (sigma 4) `\Windows\Temp\` corpus 7 (sigma 7) `\inetpub\wwwroot\` corpus 2 (sigma 2)
`TargetImage`	ends_with	`\lsass.exe` corpus 13 (sigma 13)

Neighbors

Broader alternatives (more inclusive than this rule)

These rules match a superset of what this rule catches. They cover the same events plus more. Use them if you want wider coverage and can absorb more false positives.

Potentially Suspicious GrantedAccess Flags On LSASS [sigma] (drops 1 filter this rule applies) (first-stage match only; downstream stages may differ)