Name:Cisco Secure Firewall - Connection to File Sharing Domain id:f7e5e792-d907-46c1-a58e-4ff974dc462a version:1 date:2025-04-01 author:Nasreddine Bencherchali, Splunk status:production type:Anomaly Description:The following analytic detects outbound connections to commonly abused file sharing and pastebin-style hosting domains. It leverages Cisco Secure Firewall Threat Defense logs and focuses on allowed connections (action=Allow) where the url field matches a list of known data hosting or temporary storage services. While many of these platforms serve legitimate purposes, they are frequently leveraged by adversaries for malware delivery, data exfiltration, command and control (C2) beacons, or staging of encoded payloads. This analytic is valuable for identifying potential abuse of legitimate infrastructure as part of an attacker's kill chain. If confirmed malicious, this activity may indicate tool staging, credential dumping, or outbound data leaks over HTTP(S).
Data_source:
search:`cisco_secure_firewall` action=Allow EventType=ConnectionEvent url IN ("*//objects.githubusercontent.com*", "*anonfiles.com*", "*cdn.discordapp.com*", "*ddns.net*", "*dl.dropboxusercontent.com*", "*ghostbin.co*", "*glitch.me*", "*gofile.io*", "*hastebin.com*", "*mediafire.com*", "*mega.nz*", "*onrender.com*", "*pages.dev*", "*paste.ee*", "*pastebin.com*", "*pastebin.pl*", "*pastetext.net*", "*privatlab.com*", "*privatlab.net*", "*send.exploit.in*", "*sendspace.com*", "*storage.googleapis.com*", "*storjshare.io*", "*supabase.co*", "*temp.sh*", "*transfer.sh*", "*trycloudflare.com*", "*ufile.io*", "*w3spaces.com*", "*workers.dev*") | stats count min(_time) as firstTime max(_time) as lastTime Values(src_port) as src_port Values(dest) as dest Values(dest_port) as dest_port Values(rule) as rule Values(url) as url Values(EVE_Process) as EVE_Process by src_ip, transport, action | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `cisco_secure_firewall___connection_to_file_sharing_domain_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:Legitimate users and applications may use these domains for benign purposes such as file transfers, collaborative development, or storing public content.
Developer tools, browser extensions, or open-source software may connect to githubusercontent.com or cdn.discordapp.com as part of normal operation.
It is recommended to review the associated process (`EVE_Process`), user behavior, and frequency of access before classifying the activity as suspicious.
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: - 'T1071.001' - 'T1090.002' - 'T1105' - 'T1567.002' - 'T1588.002' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' security_domain:network
