Emerging Threathightest
UNC4841 - Download Tar File From Untrusted Direct IP Via Wget
Detects execution of "wget" to download a "tar" from an IP address that doesn't have a trusted certificate. As seen used by UNC4841 during their Barracuda ESG zero day exploitation.
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Launch
Emerging Threat
Active Threat
Developed to detect an active or emerging threat. Prioritize investigation of any alerts and correlate with threat intelligence.
Log Source
LinuxProcess Creation
ProductLinux← raw: linux
CategoryProcess Creation← raw: process_creation
Events generated when a new process is spawned on the system. Covers command-line arguments, parent/child relationships, and process metadata.
Detection Logic
Detection Logic2 selectors
detection:
selection:
Image|endswith: '/wget'
CommandLine|re: 'https://[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'
CommandLine|contains: '--no-check-certificate'
CommandLine|endswith: '.tar'
filter_main_local_ips:
# Note: Uncomment this filter if you want to exclude local IPs
CommandLine|contains:
- 'https://10.' # 10.0.0.0/8
- 'https://192.168.' # 192.168.0.0/16
- 'https://172.16.' # 172.16.0.0/12
- 'https://172.17.'
- 'https://172.18.'
- 'https://172.19.'
- 'https://172.20.'
- 'https://172.21.'
- 'https://172.22.'
- 'https://172.23.'
- 'https://172.24.'
- 'https://172.25.'
- 'https://172.26.'
- 'https://172.27.'
- 'https://172.28.'
- 'https://172.29.'
- 'https://172.30.'
- 'https://172.31.'
- 'https://127.' # 127.0.0.0/8
- 'https://169.254.' # 169.254.0.0/16
condition: selection and not 1 of filter_main_*False Positives
Unknown
False positive likelihood has not been assessed. Additional context may be needed during triage.
References
MITRE ATT&CK
Tactics
Other
detection.emerging-threats
Rule Metadata
Rule ID
23835beb-ec38-4e74-a5d4-b99af6684e91
Status
test
Level
high
Type
Emerging Threat
Created
Fri Jun 16
Path
rules-emerging-threats/2023/TA/UNC4841-Barracuda-ESG-Zero-Day-Exploitation/proc_creation_lnx_apt_unc4841_wget_download_tar_files_direct_ip.yml
Raw Tags
attack.defense-evasionattack.t1140detection.emerging-threats