Name:Linux Auditd Unix Shell Configuration Modification id:66f737c6-3f7f-46ed-8e9b-cc0e5bf01f04 version:2 date:2024-09-30 author:Teoderick Contreras, Splunk status:production type:TTP Description:The following analytic detects suspicious modifications to Unix shell configuration files, which may indicate an attempt to alter system behavior or gain unauthorized access. Unix shell configuration files, such as `.bashrc` or `.profile`, control user environment settings and command execution. Unauthorized changes to these files can be used to execute malicious commands, escalate privileges, or hide malicious activities. By monitoring for unusual or unauthorized modifications to shell configuration files, this analytic helps identify potential security threats, allowing security teams to respond quickly and mitigate risks. Data_source:
-Linux Auditd Path
search:`linux_auditd` type=PATH name IN ("/etc/profile", "/etc/shells", "/etc/profile.d", "/etc/bash.bashrc", "/etc/bashrc", "/etc/zsh/zprofile", "/etc/zsh/zshrc", "/etc/zsh/zlogin", "/etc/zsh/zlogout", "/etc/csh.cshrc", "/etc/csh.login", "/root/.bashrc", "/root/.bash_profile", "root/.profile", "/root/.zshrc", "/root/.zprofile", "/home/*/.bashrc", "/home/*/.zshrc", "/home/*/.bash_profile", "/home/*/.zprofile", "/home/*/.profile", "/home/*/.bash_login", "/home/*/.bash_logout", "/home/*/.zlogin", "/home/*/.zlogout") | rename host as dest | stats count min(_time) as firstTime max(_time) as lastTime by name nametype OGID type dest | `security_content_ctime(firstTime)`| `security_content_ctime(lastTime)`| `linux_auditd_unix_shell_configuration_modification_filter`
how_to_implement:To implement this detection, the process begins by ingesting auditd data, that consist SYSCALL, TYPE, EXECVE and PROCTITLE events, which captures command-line executions and process details on Unix/Linux systems. These logs should be ingested and processed using Splunk Add-on for Unix and Linux (https://splunkbase.splunk.com/app/833), which is essential for correctly parsing and categorizing the data. The next step involves normalizing the field names to match the field names set by the Splunk Common Information Model (CIM) to ensure consistency across different data sources and enhance the efficiency of data modeling. This approach enables effective monitoring and detection of linux endpoints where auditd is deployed known_false_positives:Administrator or network operator can use this application for automation purposes. Please update the filter macros to remove false positives. References: -https://www.splunk.com/en_us/blog/security/deep-dive-on-persistence-privilege-escalation-technique-and-detection-in-linux-platform.html -https://github.com/peass-ng/PEASS-ng/tree/master/linPEAS drilldown_searches: name:'View the detection results for - "$dest$"' search:'%original_detection_search% | search dest = "$dest$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$dest$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") starthoursago=168 | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' tags: analytic_story: - 'Linux Living Off The Land' - 'Linux Privilege Escalation' - 'Linux Persistence Techniques' - 'Compromised Linux Host' asset_type:Endpoint confidence:80 impact:80 message:A [$type$] event occured on host - [$dest$] to modify the unix shell configuration file. mitre_attack_id: - 'T1546.004' - 'T1546' observable: name:'dest' type:'Endpoint' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'name' - 'nametype' - 'OGID' risk_score:25 security_domain:endpoint
