Unmount Share Via Net.EXE

Severity: low
Author: oscd.community, @redcanary, Zach Stanford @svch0st
Source: upstream

Detects when when a mounted share is removed. Adversaries may remove share connections that are no longer useful in order to clean up traces of their operation

MITRE ATT&CK coverage

Tactic	Techniques
Defense Evasion	`T1070.005` Indicator Removal: Network Share Connection Removal

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `all of selection_img`

or:
Image|endswith: '\net.exe'
Image|endswith: '\net1.exe'
OriginalFileName: net.exe
OriginalFileName: net1.exe

Stage 2: `all of selection_cli`

CommandLine|contains: '/delete'
CommandLine|contains: share

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
`CommandLine`	match	`/delete` corpus 4 (sigma 4) `share`
`Image`	ends_with	`\net.exe` corpus 27 (sigma 27) `\net1.exe` corpus 25 (sigma 25)
`OriginalFileName`	eq	`net.exe` corpus 16 (sigma 16) `net1.exe` corpus 16 (sigma 16)