Adobe Hijack Persistence

  1[metadata]
  2creation_date = "2020/02/18"
  3integration = ["endpoint", "windows", "sentinel_one_cloud_funnel", "m365_defender"]
  4maturity = "production"
  5updated_date = "2025/03/20"
  6
  7[transform]
  8[[transform.osquery]]
  9label = "Osquery - Retrieve DNS Cache"
 10query = "SELECT * FROM dns_cache"
 11
 12[[transform.osquery]]
 13label = "Osquery - Retrieve All Services"
 14query = "SELECT description, display_name, name, path, pid, service_type, start_type, status, user_account FROM services"
 15
 16[[transform.osquery]]
 17label = "Osquery - Retrieve Services Running on User Accounts"
 18query = """
 19SELECT description, display_name, name, path, pid, service_type, start_type, status, user_account FROM services WHERE
 20NOT (user_account LIKE '%LocalSystem' OR user_account LIKE '%LocalService' OR user_account LIKE '%NetworkService' OR
 21user_account == null)
 22"""
 23
 24[[transform.osquery]]
 25label = "Osquery - Retrieve Service Unsigned Executables with Virustotal Link"
 26query = """
 27SELECT concat('https://www.virustotal.com/gui/file/', sha1) AS VtLink, name, description, start_type, status, pid,
 28services.path FROM services JOIN authenticode ON services.path = authenticode.path OR services.module_path =
 29authenticode.path JOIN hash ON services.path = hash.path WHERE authenticode.result != 'trusted'
 30"""
 31
 32
 33[rule]
 34author = ["Elastic"]
 35description = "Detects writing executable files that will be automatically launched by Adobe on launch."
 36from = "now-9m"
 37index = [
 38    "winlogbeat-*",
 39    "logs-endpoint.events.file-*",
 40    "logs-windows.sysmon_operational-*",
 41    "endgame-*",
 42    "logs-sentinel_one_cloud_funnel.*",
 43    "logs-m365_defender.event-*",
 44]
 45language = "eql"
 46license = "Elastic License v2"
 47name = "Adobe Hijack Persistence"
 48note = """## Triage and analysis
 49
 50### Investigating Adobe Hijack Persistence
 51
 52Attackers can replace the `RdrCEF.exe` executable with their own to maintain their access, which will be launched whenever Adobe Acrobat Reader is executed.
 53
 54> **Note**:
 55> This investigation guide uses the [Osquery Markdown Plugin](https://www.elastic.co/guide/en/security/current/invest-guide-run-osquery.html) introduced in Elastic Stack version 8.5.0. Older Elastic Stack versions will display unrendered Markdown in this guide.
 56
 57#### Possible investigation steps
 58
 59- 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.
 60- Identify the user account that performed the action and whether it should perform this kind of action.
 61- Investigate other alerts associated with the user/host during the past 48 hours.
 62- Assess whether this behavior is prevalent in the environment by looking for similar occurrences across hosts.
 63- Examine the host for derived artifacts that indicate suspicious activities:
 64  - Analyze the file using a private sandboxed analysis system.
 65  - Observe and collect information about the following activities in both the sandbox and the alert subject host:
 66    - Attempts to contact external domains and addresses.
 67      - Use the Elastic Defend network events to determine domains and addresses contacted by the subject process by filtering by the process' `process.entity_id`.
 68      - Examine the DNS cache for suspicious or anomalous entries.
 69        - $osquery_0
 70    - Use the Elastic Defend registry events to examine registry keys accessed, modified, or created by the related processes in the process tree.
 71    - Examine the host services for suspicious or anomalous entries.
 72      - $osquery_1
 73      - $osquery_2
 74      - $osquery_3
 75  - 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.
 76- Investigate potentially compromised accounts. Analysts can do this by searching for login events (for example, 4624) to the target host after the registry modification.
 77
 78### False positive analysis
 79
 80- This activity is unlikely to happen legitimately. Benign true positives (B-TPs) can be added as exceptions if necessary.
 81
 82### Response and remediation
 83
 84- Initiate the incident response process based on the outcome of the triage.
 85- Isolate the involved host to prevent further post-compromise behavior.
 86- If the triage identified malware, search the environment for additional compromised hosts.
 87  - Implement temporary network rules, procedures, and segmentation to contain the malware.
 88  - Stop suspicious processes.
 89  - Immediately block the identified indicators of compromise (IoCs).
 90  - Inspect the affected systems for additional malware backdoors like reverse shells, reverse proxies, or droppers that attackers could use to reinfect the system.
 91- Remove and block malicious artifacts identified during triage.
 92- Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and malware components.
 93- 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.
 94- Determine the initial vector abused by the attacker and take action to prevent reinfection through the same vector.
 95- 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).
 96"""
 97references = ["https://twitter.com/pabraeken/status/997997818362155008"]
 98risk_score = 21
 99rule_id = "2bf78aa2-9c56-48de-b139-f169bf99cf86"
100setup = """## Setup
101
102If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2,
103events will not define `event.ingested` and default fallback for EQL rules was not added until version 8.2.
104Hence for this rule to work effectively, users will need to add a custom ingest pipeline to populate
105`event.ingested` to @timestamp.
106For more details on adding a custom ingest pipeline refer - https://www.elastic.co/guide/en/fleet/current/data-streams-pipeline-tutorial.html
107"""
108severity = "low"
109tags = [
110    "Domain: Endpoint",
111    "OS: Windows",
112    "Use Case: Threat Detection",
113    "Tactic: Persistence",
114    "Resources: Investigation Guide",
115    "Data Source: Elastic Endgame",
116    "Data Source: Elastic Defend",
117    "Data Source: Sysmon",
118    "Data Source: SentinelOne",
119    "Data Source: Microsoft Defender for Endpoint",
120]
121timestamp_override = "event.ingested"
122type = "eql"
123
124query = '''
125file where host.os.type == "windows" and event.type == "creation" and
126  file.path : ("?:\\Program Files (x86)\\Adobe\\Acrobat Reader DC\\Reader\\AcroCEF\\RdrCEF.exe",
127               "?:\\Program Files\\Adobe\\Acrobat Reader DC\\Reader\\AcroCEF\\RdrCEF.exe") and
128  not process.name : "msiexec.exe"
129'''
130
131
132[[rule.threat]]
133framework = "MITRE ATT&CK"
134[[rule.threat.technique]]
135id = "T1554"
136name = "Compromise Host Software Binary"
137reference = "https://attack.mitre.org/techniques/T1554/"
138
139[[rule.threat.technique]]
140id = "T1574"
141name = "Hijack Execution Flow"
142reference = "https://attack.mitre.org/techniques/T1574/"
143[[rule.threat.technique.subtechnique]]
144id = "T1574.010"
145name = "Services File Permissions Weakness"
146reference = "https://attack.mitre.org/techniques/T1574/010/"
147
148
149
150[rule.threat.tactic]
151id = "TA0003"
152name = "Persistence"
153reference = "https://attack.mitre.org/tactics/TA0003/"