Adobe Hijack Persistence

  1[metadata]
  2creation_date = "2020/02/18"
  3integration = ["endpoint", "windows"]
  4maturity = "production"
  5updated_date = "2024/03/28"
  6min_stack_comments = "New fields added: required_fields, related_integrations, setup"
  7min_stack_version = "8.3.0"
  8
  9[transform]
 10[[transform.osquery]]
 11label = "Osquery - Retrieve DNS Cache"
 12query = "SELECT * FROM dns_cache"
 13
 14[[transform.osquery]]
 15label = "Osquery - Retrieve All Services"
 16query = "SELECT description, display_name, name, path, pid, service_type, start_type, status, user_account FROM services"
 17
 18[[transform.osquery]]
 19label = "Osquery - Retrieve Services Running on User Accounts"
 20query = """
 21SELECT description, display_name, name, path, pid, service_type, start_type, status, user_account FROM services WHERE
 22NOT (user_account LIKE '%LocalSystem' OR user_account LIKE '%LocalService' OR user_account LIKE '%NetworkService' OR
 23user_account == null)
 24"""
 25
 26[[transform.osquery]]
 27label = "Osquery - Retrieve Service Unsigned Executables with Virustotal Link"
 28query = """
 29SELECT concat('https://www.virustotal.com/gui/file/', sha1) AS VtLink, name, description, start_type, status, pid,
 30services.path FROM services JOIN authenticode ON services.path = authenticode.path OR services.module_path =
 31authenticode.path JOIN hash ON services.path = hash.path WHERE authenticode.result != 'trusted'
 32"""
 33
 34
 35[rule]
 36author = ["Elastic"]
 37description = "Detects writing executable files that will be automatically launched by Adobe on launch."
 38from = "now-9m"
 39index = ["winlogbeat-*", "logs-endpoint.events.file-*", "logs-windows.sysmon_operational-*", "endgame-*"]
 40language = "eql"
 41license = "Elastic License v2"
 42name = "Adobe Hijack Persistence"
 43note = """## Triage and analysis
 44
 45### Investigating Adobe Hijack Persistence
 46
 47Attackers can replace the `RdrCEF.exe` executable with their own to maintain their access, which will be launched whenever Adobe Acrobat Reader is executed.
 48
 49> **Note**:
 50> This investigation guide uses the [Osquery Markdown Plugin](https://www.elastic.co/guide/en/security/master/invest-guide-run-osquery.html) introduced in Elastic Stack version 8.5.0. Older Elastic Stack versions will display unrendered Markdown in this guide.
 51
 52#### Possible investigation steps
 53
 54- 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.
 55- Identify the user account that performed the action and whether it should perform this kind of action.
 56- Investigate other alerts associated with the user/host during the past 48 hours.
 57- Assess whether this behavior is prevalent in the environment by looking for similar occurrences across hosts.
 58- Examine the host for derived artifacts that indicate suspicious activities:
 59  - Analyze the file using a private sandboxed analysis system.
 60  - Observe and collect information about the following activities in both the sandbox and the alert subject host:
 61    - Attempts to contact external domains and addresses.
 62      - Use the Elastic Defend network events to determine domains and addresses contacted by the subject process by filtering by the process' `process.entity_id`.
 63      - Examine the DNS cache for suspicious or anomalous entries.
 64        - $osquery_0
 65    - Use the Elastic Defend registry events to examine registry keys accessed, modified, or created by the related processes in the process tree.
 66    - Examine the host services for suspicious or anomalous entries.
 67      - $osquery_1
 68      - $osquery_2
 69      - $osquery_3
 70  - Retrieve the files' SHA-256 hash values using the PowerShell `Get-FileHash` cmdlet and search for the existence and reputation of the hashes in resources like VirusTotal, Hybrid-Analysis, CISCO Talos, Any.run, etc.
 71- Investigate potentially compromised accounts. Analysts can do this by searching for login events (for example, 4624) to the target host after the registry modification.
 72
 73### False positive analysis
 74
 75- This activity is unlikely to happen legitimately. Benign true positives (B-TPs) can be added as exceptions if necessary.
 76
 77### Response and remediation
 78
 79- Initiate the incident response process based on the outcome of the triage.
 80- Isolate the involved host to prevent further post-compromise behavior.
 81- If the triage identified malware, search the environment for additional compromised hosts.
 82  - Implement temporary network rules, procedures, and segmentation to contain the malware.
 83  - Stop suspicious processes.
 84  - Immediately block the identified indicators of compromise (IoCs).
 85  - Inspect the affected systems for additional malware backdoors like reverse shells, reverse proxies, or droppers that attackers could use to reinfect the system.
 86- Remove and block malicious artifacts identified during triage.
 87- Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and malware components.
 88- 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.
 89- Determine the initial vector abused by the attacker and take action to prevent reinfection through the same vector.
 90- 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).
 91"""
 92references = ["https://twitter.com/pabraeken/status/997997818362155008"]
 93risk_score = 21
 94rule_id = "2bf78aa2-9c56-48de-b139-f169bf99cf86"
 95setup = """## Setup
 96
 97If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2,
 98events will not define `event.ingested` and default fallback for EQL rules was not added until version 8.2.
 99Hence for this rule to work effectively, users will need to add a custom ingest pipeline to populate
100`event.ingested` to @timestamp.
101For more details on adding a custom ingest pipeline refer - https://www.elastic.co/guide/en/fleet/current/data-streams-pipeline-tutorial.html
102"""
103severity = "low"
104tags = ["Domain: Endpoint", "OS: Windows", "Use Case: Threat Detection", "Tactic: Persistence", "Resources: Investigation Guide", "Data Source: Elastic Endgame", "Data Source: Elastic Defend", "Data Source: Sysmon"]
105timestamp_override = "event.ingested"
106type = "eql"
107
108query = '''
109file where host.os.type == "windows" and event.type == "creation" and
110  file.path : ("?:\\Program Files (x86)\\Adobe\\Acrobat Reader DC\\Reader\\AcroCEF\\RdrCEF.exe",
111               "?:\\Program Files\\Adobe\\Acrobat Reader DC\\Reader\\AcroCEF\\RdrCEF.exe") and
112  not process.name : "msiexec.exe"
113'''
114
115
116[[rule.threat]]
117framework = "MITRE ATT&CK"
118[[rule.threat.technique]]
119id = "T1574"
120name = "Hijack Execution Flow"
121reference = "https://attack.mitre.org/techniques/T1574/"
122[[rule.threat.technique.subtechnique]]
123id = "T1574.010"
124name = "Services File Permissions Weakness"
125reference = "https://attack.mitre.org/techniques/T1574/010/"
126
127[[rule.threat.technique]]
128id = "T1554"
129name = "Compromise Client Software Binary"
130reference = "https://attack.mitre.org/techniques/T1554/"
131
132
133
134[rule.threat.tactic]
135id = "TA0003"
136name = "Persistence"
137reference = "https://attack.mitre.org/tactics/TA0003/"