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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.

Description

This Malware Analysis Report (MAR) is the result of analytic efforts between Department of Homeland Security (DHS), the Federal Bureau of Investigation (FBI), and the Department of Defense (DoD). Working with U.S. Government partners, DHS, FBI, and DoD identified Trojan malware variants used by the North Korean government. This malware variant has been identified as SLICKSHOES. 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, FBI, and DoD 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 sample is a Themida-packed dropper that decodes and drops a file “C:\Windows\Web\taskenc.exe” which is a Themida-packed beaconing implant. The beaconing implant does not execute the dropped file nor does it schedule any tasks to run the malware. The dropped beaconing implant uses an indigenous network encoding algorithm and is capable of many features including conducting system surveys, file upload/download, process and command execution, and screen captures.

For a downloadable copy of IOCs, see MAR-10265965-2.v1.stix.

Submitted Files (1)

fdb87add07d3459c43cfa88744656f6c00effa6b7ec92cb7c8b911d233aeb4ac (CCA9FBB11C194FC53015185B741887…)

IPs (1)

188.165.37.168

fdb87add07d3459c43cfa88744656f6c00effa6b7ec92cb7c8b911d233aeb4ac

Tags

emotettrojan

Details

Antivirus

YARA Rules

No matches found.

ssdeep Matches

No matches found.

PE Metadata

PE Sections

Relationships

Description

This sample is a Themida-packed dropper that decodes and drops an embedded file (MD5: B57DB76CC1C0175C4F18EA059D9E2AB2 / SHA256: 7250ccf4fad4d83d087a03d0dd67d1c00bf6cb8e7fa718140507a9d5ffa50b54) to C:\Windows\Web\taskenc.exe. This dropper does not execute the dropped file or create any auto-run keys or scheduled tasks to execute it.

The dropped file (taskenc.exe) is a Themida-packed beaconing implant with RAT functionality. The implant beacons to a hardcoded IP (188.165.37.168) over the hardcoded TCP port 80 every 60 seconds. The initial beacon contains the string “ApolloZeus” as well as victim information, including OS version, user name, and IP address. All traffic, including the beacon, is encoded with an indigenous encoding algorithm. Due to the way the implant decodes the hardcoded string “ApolloZeus” in-place in memory, the first beacon contains the string in plaintext, the second beacon will contain the string encoded, and so on. This is probably unintended and an oversight by the developers.

–Begin Packet Format–
[8 Bytes data length][2Byte Opcode][data]
–End Packet Format–

–Begin Victim Information–
OS Version
User name
IP address
–End Victim Information–

A Python3 script for decoding the traffic is displayed below:

–Begin Python3 Script–
def decode(enc):
dec = b’’
key1 = 0x49;
key2 = 0x1310a024;
key3 = 0xa323da32;

for e in enc:
   dec += chr((ord(e) ^ key3 ^ key1) & 0xff)
   tmp1 = key3 >> 8
   key1 = (key2>>0x10) & (key2>>8) & key2 ^ (key3>>0x10) & tmp1 ^ key3 & key1 ^ (key3>>0x18);
   tmp2 = key3 * 2 ^ key3;
   key3 = key2 << 0x18 | key3 >> 8;
   key2 = (tmp2 & 0x1fe) << 0x16 | key2 >> 8;
return dec
–End Python3 Script–

Screenshots

188.165.37.168

Ports

Relationships

Description

Hardcoded C2 address used in implant.

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”.

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/

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.

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

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.