Detects writing executable files that will be automatically launched by Adobe on launch.
Rule type: eql
Risk score: 21
Runs every: 5m
Maximum alerts per execution: 100
- Threat Detection
Rule license: Elastic License v2
## Triage and analysis ### Investigating Adobe Hijack Persistence Attackers can replace the `RdrCEF.exe` executable with their own to maintain their access, which will be launched whenever Adobe Acrobat Reader is executed. #### 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. - Identify the user account that performed the action and whether it should perform this kind of action. - Investigate other alerts associated with the user/host during the past 48 hours. - Assess whether this behavior is prevalent in the environment by looking for similar occurrences across hosts. - Retrieve the file 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 task 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 - This activity is unlikely to happen legitimately. Benign true positives (B-TPs) can be added as exceptions if necessary. ### 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. - 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. - Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and malware components. - 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. - 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).
file where event.type == "creation" and file.path : ("?:\\Program Files (x86)\\Adobe\\Acrobat Reader DC\\Reader\\AcroCEF\\RdrCEF.exe", "?:\\Program Files\\Adobe\\Acrobat Reader DC\\Reader\\AcroCEF\\RdrCEF.exe") and not process.name : "msiexec.exe"
Framework: MITRE ATT&CKTM
- Name: Persistence
- ID: TA0003
- Reference URL: https://attack.mitre.org/tactics/TA0003/
- Name: Hijack Execution Flow
- ID: T1574
- Reference URL: https://attack.mitre.org/techniques/T1574/
- Name: Services File Permissions Weakness
- ID: T1574.010
- Reference URL: https://attack.mitre.org/techniques/T1574/010/