Private Keys Reconnaissance Via CommandLine Tools

Severity: medium
Author: frack113, Nasreddine Bencherchali (Nextron Systems)
Source: upstream

Adversaries may search for private key certificate files on compromised systems for insecurely stored credential

MITRE ATT&CK coverage

Tactic	Techniques
Credential Access	`T1552.004` Unsecured Credentials: Private Keys

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `selection_ext`

or:
CommandLine|contains: .asc
CommandLine|contains: .cer
CommandLine|contains: .gpg
CommandLine|contains: .key
CommandLine|contains: .p12
CommandLine|contains: .p7b
CommandLine|contains: .pem
CommandLine|contains: .pfx
CommandLine|contains: .pgp
CommandLine|contains: .ppk

Stage 2: `all of selection_cmd_img`

or:
Image|endswith: '\cmd.exe'
OriginalFileName: Cmd.Exe

Stage 3: `all of selection_cmd_cli`

CommandLine|contains: 'dir '

Stage 4: `all of selection_pwsh_img`

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

Stage 5: `all of selection_pwsh_cli`

CommandLine|contains: 'Get-ChildItem '

Stage 6: `selection_findstr`

or:
Image|endswith: '\findstr.exe'
OriginalFileName: FINDSTR.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
`CommandLine`	match	`.asc` `.cer` `.gpg` `.key` `.p12` `.p7b` `.pem` `.pfx` `.pgp` `.ppk` `Get-ChildItem` corpus 2 (sigma 2) `dir` corpus 4 (sigma 4)
`Image`	ends_with	`\cmd.exe` corpus 92 (sigma 92) `\findstr.exe` corpus 11 (sigma 11) `\powershell.exe` corpus 143 (sigma 143) `\pwsh.exe` corpus 140 (sigma 140)
`OriginalFileName`	eq	`Cmd.Exe` corpus 32 (sigma 30, splunk 2) `FINDSTR.EXE` corpus 10 (sigma 10) `PowerShell.EXE` corpus 64 (sigma 60, splunk 4) `pwsh.dll` corpus 72 (sigma 68, splunk 4)

Private Keys Reconnaissance Via CommandLine Tools

MITRE ATT&CK coverage

Event coverage

Stages and Predicates

Stage 1: selection_ext

Stage 2: all of selection_cmd_img

Stage 3: all of selection_cmd_cli

Stage 4: all of selection_pwsh_img

Stage 5: all of selection_pwsh_cli