North Korean ELECTRICFISH proxy malware tunnels traffic
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CISA analysis of North Korean proxy malware enabling tunneling between IP addresses via compromised systems or proxy authentication.
This CISA Malware Analysis Report (MAR) documents ELECTRICFISH, a family of proxy malware variants used by North Korea's HIDDEN COBRA actors. The malware comprises two 32-bit Windows executable variants that implement a custom protocol to tunnel traffic between source and destination IP addresses. The malware operates as a command-line utility and continuously attempts to reach both source and destination systems, allowing either side to initiate tunneling sessions. A key capability is proxy authentication support: the malware accepts command-line arguments for proxy server IP/port, username, and password, enabling it to bypass network authentication controls and establish outbound connections from systems behind corporate proxy servers. This feature allows attackers to route traffic from compromised internal systems through external destinations while maintaining persistence through proxy authentication. The malware's authentication packets use a mostly-static 34-byte header with two randomized bytes to avoid simple signature detection.
Mentioned in this report
Detection guidance
Executable in User-Writable Path Launched With Proxy and Credential Arguments
Detects a binary run from a user-writable directory with command-line arguments that supply both a proxy and credentials. This is the pattern ELECTRICFISH uses to tunnel traffic out through an authenticated corporate proxy. It generalises on the argument pattern, not on a specific filename or flag spelling. Auto-generated starting point — validate and tune in your environment before deploying. IOC matches can false-positive on shared infrastructure and decay as adversary infrastructure rotates.
title: Executable in User-Writable Path Launched With Proxy and Credential Arguments
id: 716cf7df-da07-539a-8a24-92cf5069cab9
status: experimental
description: Detects a binary run from a user-writable directory with command-line
arguments that supply both a proxy and credentials, as ELECTRICFISH-style tunnelling
utilities do to authenticate through a corporate proxy. Generalises on the argument
pattern, not on a specific filename or flag spelling.
tags:
- attack.command-and-control
- attack.t1090
- attack.t1572
logsource:
category: process_creation
product: windows
detection:
selection_path:
Image|contains:
- \Users\Public\
- \ProgramData\
- \Windows\Temp\
- \AppData\Local\Temp\
- \AppData\Roaming\
selection_proxy:
CommandLine|contains:
- proxy
selection_cred:
CommandLine|contains:
- password
- passwd
- ' -pw '
- ' -pwd '
- ' -pass '
- ' -u '
- ' -user '
selection_ip_port:
CommandLine|re: '\b(?:\d{1,3}\.){3}\d{1,3}[: ]\d{2,5}\b'
condition: all of selection_*
falsepositives:
- Portable proxy-aware download or sync tools run from AppData or ProgramData by users
or IT scripts
- Software installers that pass proxy credentials while running from a temp directory
level: medium
author: Vorant
references:
- https://www.cisa.gov/news-events/analysis-reports/ar19-252b
1 more detection for this report is in the app — the rules that match its indicators, plus the Sigma rules already converted to Splunk SPL, to Elastic where their fields map onto Elastic's integrations and to Microsoft Defender XDR KQL wherever Defender records the activity, and the YARA and Suricata. Three days of it free, no card.
Behavioural rules are generated from public reporting — validate in your environment before deploying.
Source reporting: https://www.cisa.gov/news-events/analysis-reports/ar19-252b
What this brief leaves out
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