Suspicious Invoke-WebRequest Execution

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

Detects a suspicious call to Invoke-WebRequest cmdlet where the and output is located in a suspicious location

MITRE ATT&CK coverage

Tactic	Techniques
Command & Control	`T1105` Ingress Tool Transfer

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `all of selection_img`

or:
Image|endswith: '\powershell.exe'
Image|endswith: '\powershell_ise.exe'
Image|endswith: '\pwsh.exe'
OriginalFileName: PowerShell.EXE
OriginalFileName: powershell_ise.EXE
OriginalFileName: pwsh.dll

Stage 2: `all of selection_commands`

or:
CommandLine|contains: Invoke-WebRequest
CommandLine|contains: 'curl '
CommandLine|contains: 'iwr '
CommandLine|contains: 'wget '

Stage 3: `all of selection_flags`

or:
CommandLine|contains: ' -o'
CommandLine|contains: ' -ur'

Stage 4: `all of selection_susp_locations`

or:
CommandLine|contains: '%AppData%'
CommandLine|contains: '%Public%'
CommandLine|contains: '%Temp%'
CommandLine|contains: '%tmp%'
CommandLine|contains: ':\Windows\'
CommandLine|contains: '\AppData\'
CommandLine|contains: '\Desktop\'
CommandLine|contains: '\Temp\'
CommandLine|contains: '\Users\Public\'

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	`-o` `-ur` corpus 2 (sigma 2) `%AppData%` corpus 7 (sigma 7) `%Public%` corpus 4 (sigma 4) `%Temp%` corpus 4 (sigma 4) `%tmp%` corpus 9 (sigma 9) `:\Windows\` corpus 2 (sigma 2) `Invoke-WebRequest` corpus 6 (sigma 6) `\AppData\` corpus 8 (sigma 8) `\Desktop\` corpus 11 (sigma 11) `\Temp\` corpus 7 (sigma 7) `\Users\Public\` corpus 17 (sigma 17) `curl` corpus 8 (sigma 8) `iwr` corpus 8 (sigma 8) `wget` corpus 7 (sigma 7)
`Image`	ends_with	`\powershell.exe` corpus 143 (sigma 143) `\powershell_ise.exe` corpus 27 (sigma 27) `\pwsh.exe` corpus 140 (sigma 140)
`OriginalFileName`	eq	`PowerShell.EXE` corpus 64 (sigma 60, splunk 4) `powershell_ise.EXE` corpus 8 (sigma 4, splunk 4) `pwsh.dll` corpus 72 (sigma 68, splunk 4)

Suspicious Invoke-WebRequest Execution

MITRE ATT&CK coverage

Event coverage

Stages and Predicates

Stage 1: all of selection_img

Stage 2: all of selection_commands

Stage 3: all of selection_flags

Stage 4: all of selection_susp_locations

Indicators

Stage 1: `all of selection_img`

Stage 2: `all of selection_commands`

Stage 3: `all of selection_flags`

Stage 4: `all of selection_susp_locations`