AR19-129A: MAR-10135536-21 – North Korean Tunneling Tool: ELECTRICFISH

["US-CERT" <US-CERT () ncas us-cert gov>]

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National Cyber Awareness System: AR19-129A: MAR-10135536-21  North Korean Tunneling Tool: ELECTRICFISH [ 
https://www.us-cert.gov/ncas/analysis-reports/AR19-129A ] 05/09/2019 11:58 AM EDT 
Original release date: May 09, 2019

Description

Notification

This report is provided "as is" for informational purposes only. The Department of Homeland Security (DHS) does not 
provide any warranties of any kind regarding any information contained herein. The DHS does not endorse any commercial 
product or service referenced in this bulletin or otherwise.

This document is marked TLP:WHITE--Disclosure is not limited. Sources may use TLP:WHITE when information carries 
minimal or no foreseeable risk of misuse, in accordance with applicable rules and procedures for public release. 
Subject to standard copyright rules, TLP:WHITE information may be distributed without restriction. For more information 
on the Traffic Light Protocol (TLP), see http://www.us-cert.gov/tlp.

Summary

Description

This Malware Analysis Report (MAR) is the result of analytic efforts between DHS and the Federal Bureau of 
Investigation (FBI). Working with U.S. Government partners, DHS and FBI identified a malware variant used by the North 
Korean government. This malware has been identified as ELECTRICFISH. The U.S. Government refers to malicious cyber 
activity by the North Korean government as HIDDEN COBRA. For more information on HIDDEN COBRA activity, visit 
https://www.us-cert.gov/hiddencobra.

DHS and FBI are distributing this MAR to enable network defense and reduce exposure to North Korean government 
malicious cyber activity.

This MAR includes malware descriptions related to HIDDEN COBRA, suggested response actions and recommended mitigation 
techniques. Users or administrators should flag activity associated with the malware and report the activity to the 
Cybersecurity and Infrastructure Security Agency (CISA) or the FBI Cyber Watch (CyWatch), and give the activity the 
highest priority for enhanced mitigation.

This report provides analysis of one malicious 32-bit Windows executable file. The malware implements a custom protocol 
that allows traffic to be funneled between a source and a destination Internet Protocol (IP) address. The malware 
continuously attempts to reach out to the source and the designation system, which allows either side to initiate a 
funneling session. The malware can be configured with a proxy server/port and proxy username and password. This feature 
allows connectivity to a system sitting inside of a proxy server, which allows the actor to bypass the compromised 
systems required authentication to reach outside of the network.

For a downloadable copy of IOCs, see:


  * MAR-10135536-21.stix [ https://www.us-cert.gov/sites/default/files/publications/MAR-10135536-21.stix.xml ] 

Submitted Files (1)

a1260fd3e9221d1bc5b9ece6e7a5a98669c79e124453f2ac58625085759ed3bb (a1260fd3e9221d1bc5b9ece6e7a5a9...)

Findings

a1260fd3e9221d1bc5b9ece6e7a5a98669c79e124453f2ac58625085759ed3bb

Details

Name a1260fd3e9221d1bc5b9ece6e7a5a98669c79e124453f2ac58625085759ed3bb Size 1422336 bytes Type PE32 executable (GUI) 
Intel 80386, for MS Windows MD5 8d9123cd2648020292b5c35edc9ae22e SHA1 0939363ff55d914e92635e5f693099fb28047602 SHA256 
a1260fd3e9221d1bc5b9ece6e7a5a98669c79e124453f2ac58625085759ed3bb SHA512 
646697e3d5146e05a221183f6c9f00f5eb38400ef9a2f83bfd0fcf2f8af1a7efff99c0a3486740c745ce6cf0939c4f0678cb818cbbff8ed2b28a703fe8d823bb
 ssdeep 24576:HsO8RKL6OLnWZGFbHq0aMow5Q3gkD/74tU3hYPgP5IyrMsEOhVRpxHkADUHEPbzJ:0KjKHMbO3pkoBIyIstVRpxHL1bF Entropy 
6.703195 

Antivirus

BitDefender Gen:Variant.Ursu.349885Unclassified Emsisoft Gen:Variant.Ursu.349885 (B) 

Yara Rules

No matches found.

ssdeep Matches

No matches found.

PE Metadata

Compile Date 2018-09-29 11:55:36-04:00 Import Hash 3549cfa19e60aa9239f79d80e19279fa 

PE Sections

MD5 Name Raw Size Entropy 08bb17d8e839e7fc92426e813a696e73 header 1024 2.590786 6c3daca3c522ab98a8ac12a45087297c .text 
983040 6.595856 3d3d7962d16652002018640a3fa27d44 .rdata 340480 6.187858 b7f382ea7e6c9c8e737cb92551341e64 .data 37888 
4.714377 871fb8486e5ea3307ff7b65ddf46518a .rsrc 512 5.112624 382715f8e776a544bf70f843a52e3ff2 .reloc 59392 6.015022 

Packers/Compilers/Cryptors

Microsoft Visual C++ ?.? 

Process List

Process PID PPID lsass.exe 488 (384) a1260fd3e9221d1bc5b9ece6e7a5a98669c79e124453f2ac58625085759ed3bb.exe 3052 (3024) 

Description

This file is a malicious Windows 32-bit executable. The application is a command-line utility and its primary purpose 
is to funnel traffic between two IP addresses. The application accepts command-line arguments allowing it to be 
configured with a destination IP address and port, a source IP address and port, a proxy IP address and port, and a 
user name and password, which can be utilized to authenticate with a proxy server. It will attempt to establish TCP 
sessions with the source IP address and the destination IP address. If a connection is made to both the source and 
destination IPs, this malicious utility will implement a custom protocol, which will allow traffic to rapidly and 
efficiently be funneled between two machines. If necessary, the malware can authenticate with a proxy to be able to 
reach the destination IP address. A configured proxy server is not required for this utility.

--Begin Example Usage--
Source IP/Port: 23.23.23.23:92
Dest IP/Port: 24.24.24.24:92
Proxy IP/Port: 192.1.1.3:92
Proxy User Name: test
Proxy Password: testpw

a12.exe -s 23.23.23.23:92 -d 24.24.24.24:92 -p 192.1.1.3:92 -u test -pw testpw
--End Example Usage--

After the malware authenticates with the configured proxy, it will immediately attempt to establish a session with the 
destination IP address, located outside of the target network and the source IP address. The header of the initial 
authentication packet, sent to both the source and destination systems, will be static except for two random bytes. 
Everything within this 34-byte header is static except for the bytes 0X2B6E, which will change during each connection 
attempt. Displayed below (and displayed in Figure 7) is the packet header.

--Begin Authentication Packet Sent to Destination System--
6161616162626262636363636464646400000000000000002B6E0000040000009210
--End Authentication Packet Sent to Destination System--

Screenshots
Figure 1 - Screenshot of the malware authenticating with the proxy server configured at command prompt. 

*Figure 1 - *Screenshot of the malware authenticating with the proxy server configured at command prompt.

*Figure 2 - *Screenshot of the malware building the authentication packet that will be sent to the destination system. 
It must begin with the static value "aaaa" for it to be accepted by the utility.

Figure 3 - Screenshot of the malware evaluating a received authentication packet. 

*Figure 3 - *Screenshot of the malware evaluating a received authentication packet.

Figure 4 - Screenshot of the malware system authentication packet to the source/destination system. 

*Figure 4 - *Screenshot of the malware system authentication packet to the source/destination system.

Figure 5 - Screenshot of the authentication packet sent to the source/destination system during analysis. The malware 
will attempt to tunnel traffic between the source and destination systems specified in the command prompt. 

*Figure 5 - *Screenshot of the authentication packet sent to the source/destination system during analysis. The malware 
will attempt to tunnel traffic between the source and destination systems specified in the command prompt.

Figure 6 - Screenshot of the malware generating two-bytes of random data which will be included in the authentication 
packet sent to the source/destination systems. 

*Figure 6 - *Screenshot of the malware generating two-bytes of random data which will be included in the authentication 
packet sent to the source/destination systems.

*Figure 7 - *Screenshot of the authentication packet sent to "source" system with lab environment. Malware will attempt 
to tunnel traffic between the source and destination systems specified at command prompt.

Recommendations

CISA recommends that users and administrators consider using the following best practices to strengthen the security 
posture of their organization's systems. Any configuration changes should be reviewed by system owners and 
administrators prior to implementation to avoid unwanted impacts.


  * Maintain up-to-date antivirus signatures and engines. 
  * Keep operating system patches up-to-date. 
  * Disable File and Printer sharing services. If these services are required, use strong passwords or Active Directory 
authentication. 
  * Restrict users' ability (permissions) to install and run unwanted software applications. Do not add users to the 
local administrators group unless required. 
  * Enforce a strong password policy and implement regular password changes. 
  * Exercise caution when opening e-mail attachments even if the attachment is expected and the sender appears to be 
known. 
  * Enable a personal firewall on agency workstations, configured to deny unsolicited connection requests. 
  * Disable unnecessary services on agency workstations and servers. 
  * Scan for and remove suspicious e-mail attachments; ensure the scanned attachment is its "true file type" (i.e., the 
extension matches the file header). 
  * Monitor users' web browsing habits; restrict access to sites with unfavorable content. 
  * Exercise caution when using removable media (e.g., USB thumb drives, external drives, CDs, etc.). 
  * Scan all software downloaded from the Internet prior to executing. 
  * Maintain situational awareness of the latest threats and implement appropriate Access Control Lists (ACLs). 

Additional information on malware incident prevention and handling can be found in National Institute of Standards and 
Technology (NIST) Special Publication 800-83, *"Guide to Malware Incident Prevention & Handling for Desktops and 
Laptops".*

Contact Information

  * 1-888-282-0870 
  * NCCICCustomerService () us-cert gov [ https://www.us-cert.govmailto:NCCICCustomerService () us-cert gov ] (UNCLASS) 
  * us-cert () dhs sgov gov [ https://www.us-cert.govmailto:us-cert () dhs sgov gov ] (SIPRNET) 
  * us-cert () dhs ic gov [ https://www.us-cert.govmailto:us-cert () dhs ic gov ] (JWICS) 

CISA continuously strives to improve its products and services. You can help by answering a very short series of 
questions about this product at the following URL: https://us-cert.gov/forms/feedback/

Document FAQ

*What is a MIFR?* A Malware Initial Findings Report (MIFR) is intended to provide organizations with malware analysis 
in a timely manner. In most instances this report will provide initial indicators for computer and network defense. To 
request additional analysis, please contact CISA and provide information regarding the level of desired analysis.

*What is a MAR?* A Malware Analysis Report (MAR) is intended to provide organizations with more detailed malware 
analysis acquired via manual reverse engineering. To request additional analysis, please contact CISA and provide 
information regarding the level of desired analysis.

*Can I edit this document?* This document is not to be edited in any way by recipients. All comments or questions 
related to this document should be directed to the CISA at 1-888-282-0870 or soc () us-cert gov [ 
https://www.us-cert.govmailto:soc () us-cert gov ].

*Can I submit malware to CISA?* Malware samples can be submitted via three methods:


  * Web: https://malware.us-cert.gov 
  * E-Mail: submit () malware us-cert gov [ https://www.us-cert.govmailto:submit () malware us-cert gov ] 
  * FTP: ftp.malware.us-cert.gov (anonymous) 

CISA encourages you to report any suspicious activity, including cybersecurity incidents, possible malicious code, 
software vulnerabilities, and phishing-related scams. Reporting forms can be found on CISA's homepage at 
www.us-cert.gov [ http://www.us-cert.gov ].

 

Revisions

  * May 9, 2019: Initial version 
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