Name:Cisco Secure Firewall - Wget or Curl Download id:173a1cb9-1814-4128-a9dc-f29dade89957 version:1 date:2025-04-01 author:Nasreddine Bencherchali, Splunk status:production type:Anomaly Description:The following analytic detects outbound connections initiated by command-line tools such as curl or wget. It leverages Cisco Secure Firewall Threat Defense logs and identifies allowed connections (action=Allow) where either the EVE_Process or ClientApplication fields indicate use of these utilities. While curl and wget are legitimate tools commonly used for software updates and scripting, adversaries often abuse them to download payloads, retrieve additional tools, or establish staging infrastructure from compromised systems. If confirmed malicious, this behavior may indicate the download phase of an attack chain or a command-and-control utility retrieval.
Data_source:
search:`cisco_secure_firewall` EventType=ConnectionEvent action=Allow AND ( EVE_Process IN ("*curl*", "*wget*") OR ClientApplication IN ("cURL", "Wget") ) | stats count min(_time) as firstTime max(_time) as lastTime Values(rule) as rule Values(url) as url Values(dest_port) as dest_port Values(ClientApplicationVersion) as ClientApplicationVersion Values(src_port) as src_port by src_ip, dest, transport, EVE_Process, ClientApplication, action | table src_ip src_port dest dest_port transport url EVE_Process ClientApplication ClientApplicationVersion rule firstTime lastTime | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `cisco_secure_firewall___wget_or_curl_download_filter`
how_to_implement:This search requires Cisco Secure Firewall Threat Defense Logs, which
includes the ConnectionEvent EventType. This search uses an input macro named `cisco_secure_firewall`.
We strongly recommend that you specify your environment-specific configurations
(index, source, sourcetype, etc.) for Cisco Secure Firewall Threat Defense logs. Replace the macro definition
with configurations for your Splunk environment. The search also uses a post-filter
macro designed to filter out known false positives.
The logs are to be ingested using the Splunk Add-on for Cisco Security Cloud (https://splunkbase.splunk.com/app/7404).
The access policy must also enable logging.
known_false_positives:Developers, administrators, or automation tools may use `curl` or `wget` for legitimate purposes such as software installation, configuration scripts, or CI/CD tasks.
Security tools or health monitoring scripts may also use these utilities to check service availability or download updates.
Review the destination `url`, frequency, and process context to validate whether the download activity is authorized.
References: -https://www.cisco.com/c/en/us/td/docs/security/firepower/741/api/FQE/secure_firewall_estreamer_fqe_guide_740.pdf drilldown_searches: name:'View the detection results for - "$src_ip$"' search:'%original_detection_search% | search src_ip = "$src_ip$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$src_ip$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$src_ip$") 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: - 'Cisco Secure Firewall Threat Defense Analytics' asset_type:Network mitre_attack_id: - 'T1053.003' - 'T1059' - 'T1071.001' - 'T1105' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' security_domain:network
