sigma-rules/rules/windows/credential_access_lsass_memdump_handle_access.toml

[metadata]
creation_date = "2022/02/16"
maturity = "production"
updated_date = "2022/05/09"

[rule]
author = ["Elastic"]
description = """
Identifies handle requests for the Local Security Authority Subsystem Service (LSASS) object access with
specific access masks that many tools with a capability to dump memory to disk use (0x1fffff, 0x1010, 0x120089).
This rule is tool agnostic as it has been validated against a host of various LSASS dump tools such as SharpDump,
Procdump, Mimikatz, Comsvcs etc. It detects this behavior at a low level and does not depend on a specific tool or dump
file name.
"""
from = "now-9m"
index = ["winlogbeat-*", "logs-system.*"]
language = "eql"
license = "Elastic License v2"
name = "LSASS Memory Dump Handle Access"
note = """## Triage and analysis

### Investigating LSASS Memory Dump Handle Access

Local Security Authority Server Service (LSASS) is a process in Microsoft Windows operating systems that is responsible
for enforcing security policy on the system. It verifies users logging on to a Windows computer or server, handles
password changes, and creates access tokens.

Adversaries may attempt to access credential material stored in LSASS process memory. After a user logs on,the system
generates and stores a variety of credential materials in LSASS process memory. This is meant to facilitate single
sign-on (SSO) ensuring a user isn’t prompted each time resource access is requested. These credential materials can be
harvested by an adversary using administrative user or SYSTEM privileges to conduct lateral movement using 
[alternate authentication material](https://attack.mitre.org/techniques/T1550/).

#### Possible investigation steps

- Investigate the process execution chain (parent process tree) for unknown processes. Examine their executable files
for prevalence, whether they are located in expected locations, and if they are signed with valid digital signatures.
- Investigate other alerts associated with the user/host during the past 48 hours.
- Retrieve the process executable and determine if it is malicious:
  - Use a private sandboxed malware analysis system to perform analysis.
    - Observe and collect information about the following activities:
      - Attempts to contact external domains and addresses.
      - File and registry access, modification, and creation activities.
      - Service creation and launch activities.
      - Scheduled tasks creation.
  - Use the PowerShell Get-FileHash cmdlet to get the files' SHA-256 hash values.
    - Search for the existence and reputation of the hashes in resources like VirusTotal, Hybrid-Analysis, CISCO Talos, Any.run, etc.

### False positive analysis

- There should be very few or no false positives for this rule. If this activity is expected or noisy in your environment,
consider adding exceptions — preferably with a combination of user and command line conditions.
- If the process is related to antivirus or endpoint detection and response solutions, validate that it is installed on
the correct path and signed with the company's valid digital signature.

### Response and remediation

- Initiate the incident response process based on the outcome of the triage.
- Isolate the involved host to prevent further post-compromise behavior.
- Scope compromised credentials and disable the accounts.
- If the triage identified malware, search the environment for additional compromised hosts.
  - Implement temporary network rules, procedures, and segmentation to contain the malware.
  - Stop suspicious processes.
  - Immediately block the identified indicators of compromise (IoCs).
  - Inspect the affected systems for additional malware backdoors like reverse shells, reverse proxies, or droppers that
  attackers could use to reinfect the system.
- Remove and block malicious artifacts identified during triage.
- Investigate credential exposure on systems compromised or used by the attacker to ensure all compromised accounts are
identified. Reset passwords for these accounts and other potentially compromised credentials, such as email, business
systems, and web services.
- Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and
malware components.
- Determine the initial vector abused by the attacker and take action to prevent reinfection through the same vector.
- Using the incident response data, update logging and audit policies to improve the mean time to detect (MTTD) and the
mean time to respond (MTTR).

## Config

Ensure advanced audit policies for Windows are enabled, specifically:
Object Access policies [Event ID 4656](https://docs.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4656) (Handle to an Object was Requested)

```
Computer Configuration >
Policies >
Windows Settings >
Security Settings >
Advanced Audit Policies Configuration >
System Audit Policies >
Object Access >
Audit File System (Success,Failure)
Audit Handle Manipulation (Success,Failure)
```

Also, this event generates only if the object’s [SACL](https://docs.microsoft.com/en-us/windows/win32/secauthz/access-control-lists) has the required access control entry (ACE) to handle the use of specific access rights.

If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define `event.ingested` and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate `event.ingested` to @timestamp for this rule to work.
"""
references = [
    "https://docs.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4656",
    "https://twitter.com/jsecurity101/status/1227987828534956033?s=20",
    "https://attack.mitre.org/techniques/T1003/001/",
    "https://threathunterplaybook.com/notebooks/windows/06_credential_access/WIN-170105221010.html",
    "http://findingbad.blogspot.com/2017/"
]
risk_score = 73
rule_id = "208dbe77-01ed-4954-8d44-1e5751cb20de"
severity = "high"
tags = ["Elastic", "Host", "Windows", "Threat Detection", "Credential Access"]
timestamp_override = "event.ingested"
type = "eql"

query = '''
any where event.action == "File System" and event.code == "4656" and

    winlog.event_data.ObjectName : (
        "?:\\Windows\\System32\\lsass.exe",
        "\\Device\\HarddiskVolume?\\Windows\\System32\\lsass.exe",
        "\\Device\\HarddiskVolume??\\Windows\\System32\\lsass.exe") and

    /* The right to perform an operation controlled by an extended access right. */

    (winlog.event_data.AccessMask : ("0x1fffff" , "0x1010", "0x120089", "0x1F3FFF") or
     winlog.event_data.AccessMaskDescription : ("READ_CONTROL", "Read from process memory"))

     /* Common Noisy False Positives */

    and not winlog.event_data.ProcessName : (
        "?:\\Program Files\\*.exe",
        "?:\\Program Files (x86)\\*.exe",
        "?:\\Windows\\system32\\wbem\\WmiPrvSE.exe",
        "?:\\Windows\\System32\\dllhost.exe",
        "?:\\Windows\\System32\\svchost.exe",
        "?:\\Windows\\System32\\msiexec.exe",
        "?:\\ProgramData\\Microsoft\\Windows Defender\\*.exe",
        "?:\\Windows\\explorer.exe")
'''


[[rule.threat]]
framework = "MITRE ATT&CK"

[[rule.threat.technique]]
id = "T1003"
name = "OS Credential Dumping"
reference = "https://attack.mitre.org/techniques/T1003/"

    [[rule.threat.technique.subtechnique]]
    id = "T1003.001"
    name = "LSASS Memory"
    reference = "https://attack.mitre.org/techniques/T1003/001/"

[rule.threat.tactic]
id = "TA0006"
name = "Credential Access"
reference = "https://attack.mitre.org/tactics/TA0006/"