CyberWarfare / ExoWarfare

“Hidden Cobra” – U.S. Gov issues alerts about malware and IP addresses linked to North Korean cyber attacks

Thomas J Ackermann

US-CERT, the Department of Homeland Security team responsible for analyzing cybersecurity threats, has posted a warning about cyber attacks by the North Korean government, which it collectively refers to as “Hidden Cobra.” The technical alert from the FBI and Department of Homeland Security says a remote administration tool (RAT) called FALLCHILL has been deployed by Hidden Cobra since 2016 to target the aerospace, telecommunications and finance industries.

FALLCHILL allows Hidden Cobra to issue commands to a victim’s server by dual proxies, which means it can potentially perform actions like retrieving information about all installed disks, accessing files, modifying file or directory timestamps and deleting evidence that it’s been on the infected server.

The FBI and Department of Homeland Security also posted a list of IP addresses linked to Hidden Cobra. The FBI says it “has high confidence” that those IP addresses are linked to attacks that infect computer systems with Volgmer, a Trojan malware variant used by Hidden Cobra to target the government, financial, auto and media industries.

The U.S. government says Volgmer has been used to gain access to computer systems since at least 2013. Once Volgmer establishes a presence in a systems, it can gather system information, update service registry keys, download and upload files, execute commands and terminate processes and list directories, says the FBI and Department of Homeland Security.

The new warnings from US-CERT come five months after a technical alert posted in June that implicated Hidden Cobra (which has also been called Lazarus Group and Guardians of the Peace by security experts) in a series of cyber attacks that date back to 2009 and include the 2014 Sony Pictures hack.

While North Korea’s cyber espionage efforts were once dismissed by many security experts, the success of Hidden Cobra over the last few years has changed that perception, and it is now seen as a serious threat because it is able to do a lot of damage at a relatively low cost.

 

from: https://techcrunch.com/2017/11/14/u-s-government-issues-alerts-about-malware-and-ip-addresses-linked-to-north-korean-cyber-attacks/

 

Alert (TA17-318A)

HIDDEN COBRA – North Korean Remote Administration Tool: FALLCHILL

Original release date: November 14, 2017

Systems Affected

Network systems

Overview

This joint Technical Alert (TA) is the result of analytic efforts between the Department of Homeland Security (DHS) and the Federal Bureau of Investigation (FBI). Working with U.S. government partners, DHS and FBI identified Internet Protocol (IP) addresses and other indicators of compromise (IOCs) associated with a remote administration tool (RAT) used by the North Korean government—commonly known as FALLCHILL. 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.

FBI has high confidence that HIDDEN COBRA actors are using the IP addresses — listed in this report’s IOC files — to maintain a presence on victims’ networks and to further network exploitation. DHS and FBI are distributing these IP addresses to enable network defense and reduce exposure to any North Korean government malicious cyber activity.

This alert includes IOCs related to HIDDEN COBRA, IP addresses linked to systems infected with FALLCHILL malware, malware descriptions, and associated signatures. This alert also includes suggested response actions to the IOCs provided, recommended mitigation techniques, and information on reporting incidents. If users or administrators detect activity associated with the FALLCHILL malware, they should immediately flag it, report it to the DHS National Cybersecurity and Communications Integration Center (NCCIC) or the FBI Cyber Watch (CyWatch), and give it the highest priority for enhanced mitigation.

For a downloadable copy of IOCs, see:

NCCIC conducted analysis on two samples of FALLCHILL malware and produced a Malware Analysis Report (MAR). MAR-10135536-A examines the tactics, techniques, and procedures observed in the malware. For a downloadable copy of the MAR, see:

Description

According to trusted third-party reporting, HIDDEN COBRA actors have likely been using FALLCHILL malware since 2016 to target the aerospace, telecommunications, and finance industries. The malware is a fully functional RAT with multiple commands that the actors can issue from a command and control (C2) server to a victim’s system via dual proxies. FALLCHILL typically infects a system as a file dropped by other HIDDEN COBRA malware or as a file downloaded unknowingly by users when visiting sites compromised by HIDDEN COBRA actors. HIDDEN COBRA actors use an external tool or dropper to install the FALLCHILL malware-as-a-service to establish persistence. Because of this, additional HIDDEN COBRA malware may be present on systems compromised with FALLCHILL.

During analysis of the infrastructure used by FALLCHILL malware, the U.S. Government identified 83 network nodes. Additionally, using publicly available registration information, the U.S. Government identified the countries in which the infected IP addresses are registered.

Technical Details

FALLCHILL is the primary component of a C2 infrastructure that uses multiple proxies to obfuscate network traffic between HIDDEN COBRA actors and a victim’s system. According to trusted third-party reporting, communication flows from the victim’s system to HIDDEN COBRA actors using a series of proxies as shown in figure 1.

Figure 1. HIDDEN COBRA Communication Flow

FALLCHILL uses fake Transport Layer Security (TLS) communications, encoding the data with RC4 encryption with the following key: [0d 06 09 2a 86 48 86 f7 0d 01 01 01 05 00 03 82]. FALLCHILL collects basic system information and beacons the following to the C2:

  • operating system (OS) version information,
  • processor information,
  • system name,
  • local IP address information,
  • unique generated ID, and
  • media access control (MAC) address.

FALLCHILL contains the following built-in functions for remote operations that provide various capabilities on a victim’s system:

  • retrieve information about all installed disks, including the disk type and the amount of free space on the disk;
  • create, start, and terminate a new process and its primary thread;
  • search, read, write, move, and execute files;
  • get and modify file or directory timestamps;
  • change the current directory for a process or file; and
  • delete malware and artifacts associated with the malware from the infected system.

Detection and Response

This alert’s IOC files provide HIDDEN COBRA indicators related to FALLCHILL. DHS and FBI recommend that network administrators review the information provided, identify whether any of the provided IP addresses fall within their organizations’ allocated IP address space, and — if found — take necessary measures to remove the malware.

When reviewing network perimeter logs for the IP addresses, organizations may find instances of these IP addresses attempting to connect to their systems. Upon reviewing the traffic from these IP addresses, system owners may find some traffic relates to malicious activity and some traffic relates to legitimate activity.

Network Signatures and Host-Based Rules

This section contains network signatures and host-based rules that can be used to detect malicious activity associated with HIDDEN COBRA actors. Although created using a comprehensive vetting process, the possibility of false positives always remains. These signatures and rules should be used to supplement analysis and should not be used as a sole source of attributing this activity to HIDDEN COBRA actors.

Network Signatures

alert
tcp any any -> any any (msg:"Malicious SSL 01 Detected";content:"|17
03 01 00 08|";  pcre:"/\x17\x03\x01\x00\x08.{4}\x04\x88\x4d\x76/";
rev:1; sid:2;)

___________________________________________________________________________________________

alert
tcp any any -> any any (msg:"Malicious SSL 02 Detected";content:"|17
03 01 00 08|";  pcre:"/\x17\x03\x01\x00\x08.{4}\x06\x88\x4d\x76/";
rev:1; sid:3;)

___________________________________________________________________________________________

alert
tcp any any -> any any (msg:"Malicious SSL 03 Detected";content:"|17
03 01 00 08|";  pcre:"/\x17\x03\x01\x00\x08.{4}\xb2\x63\x70\x7b/";
rev:1; sid:4;)

___________________________________________________________________________________________

alert
tcp any any -> any any (msg:"Malicious SSL 04 Detected";content:"|17
03 01 00 08|";  pcre:"/\x17\x03\x01\x00\x08.{4}\xb0\x63\x70\x7b/";
rev:1; sid:5;)

___________________________________________________________________________________________

YARA Rules

The following rules were provided to NCCIC by a trusted third party for the purpose of assisting in the identification of malware associated with this alert.

THIS DHS/NCCIC MATERIAL IS FURNISHED ON AN “AS-IS” BASIS.  These rules have been tested and determined to function effectively in a lab environment, but we have no way of knowing if they may function differently in a production network.  Anyone using these rules are encouraged to test them using a data set representitive of their environment.

rule rc4_stack_key_fallchill
{
meta:
description = "rc4_stack_key"
strings:
$stack_key = { 0d 06 09 2a ?? ?? ?? ?? 86 48 86 f7 ?? ?? ?? ?? 0d 01
01 01 ?? ?? ?? ?? 05 00 03 82 41 8b c9 41 8b d1 49 8b 40 08 48 ff c2 88
4c 02 ff ff c1 81 f9 00 01 00 00 7c eb }
condition:
(uint16(0) == 0x5A4D and uint16(uint32(0x3c)) == 0x4550) and $stack_key
}

rule success_fail_codes_fallchill

{
meta:
description = "success_fail_codes"
strings:
$s0 = { 68 7a 34 12 00 }
$s1 = { ba 7a 34 12 00 }
$f0 = { 68 5c 34 12 00 }
$f1 = { ba 5c 34 12 00 }
condition:
(uint16(0) == 0x5A4D and uint16(uint32(0x3c)) == 0x4550) and (($s0 and $f0) or ($s1 and $f1))
}

___________________________________________________________________________________________

Impact

A successful network intrusion can have severe impacts, particularly if the compromise becomes public and sensitive information is exposed. Possible impacts include:

  • temporary or permanent loss of sensitive or proprietary information,
  • disruption to regular operations,
  • financial losses incurred to restore systems and files, and
  • potential harm to an organization’s reputation.

Solution

Mitigation Strategies

DHS recommends that users and administrators use the following best practices as preventive measures to protect their computer networks:

  • Use application whitelisting to help prevent malicious software and unapproved programs from running. Application whitelisting is one of the best security strategies as it allows only specified programs to run, while blocking all others, including malicious software.
  • Keep operating systems and software up-to-date with the latest patches. Vulnerable applications and operating systems are the target of most attacks. Patching with the latest updates greatly reduces the number of exploitable entry points available to an attacker.
  • Maintain up-to-date antivirus software, and scan all software downloaded from the Internet before executing.
  • Restrict users’ abilities (permissions) to install and run unwanted software applications, and apply the principle of “least privilege” to all systems and services. Restricting these privileges may prevent malware from running or limit its capability to spread through the network.
  • Avoid enabling macros from email attachments. If a user opens the attachment and enables macros, embedded code will execute the malware on the machine. For enterprises or organizations, it may be best to block email messages with attachments from suspicious sources. For information on safely handling email attachments, see Recognizing and Avoiding Email Scams. Follow safe practices when browsing the web. See Good Security Habits and Safeguarding Your Data for additional details.
  • Do not follow unsolicited web links in emails. See Avoiding Social Engineering and Phishing Attacks for more information.

Response to Unauthorized Network Access

 

Source: https://www.us-cert.gov/ncas/alerts/TA17-318A

 

 

Alert (TA17-318B)

HIDDEN COBRA – North Korean Trojan: Volgmer

Original release date: November 14, 2017 | Last revised: November 15, 2017

Systems Affected

Network systems

Overview

This joint Technical Alert (TA) is the result of analytic efforts between the Department of Homeland Security (DHS) and the Federal Bureau of Investigation (FBI). Working with U.S. government partners, DHS and FBI identified Internet Protocol (IP) addresses and other indicators of compromise (IOCs) associated with a Trojan malware variant used by the North Korean government—commonly known as Volgmer. 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.

FBI has high confidence that HIDDEN COBRA actors are using the IP addresses—listed in this report’s IOC files—to maintain a presence on victims’ networks and to further network exploitation. DHS and FBI are distributing these IP addresses to enable network defense and reduce exposure to North Korean government malicious cyber activity.

This alert includes IOCs related to HIDDEN COBRA, IP addresses linked to systems infected with Volgmer malware, malware descriptions, and associated signatures. This alert also includes suggested response actions to the IOCs provided, recommended mitigation techniques, and information on reporting incidents. If users or administrators detect activity associated with the Volgmer malware, they should immediately flag it, report it to the DHS National Cybersecurity and Communications Integration Center (NCCIC) or the FBI Cyber Watch (CyWatch), and give it the highest priority for enhanced mitigation.

For a downloadable copy of IOCs, see:

NCCIC conducted analysis on five files associated with or identified as Volgmer malware and produced a Malware Analysis Report (MAR). MAR-10135536-D examines the tactics, techniques, and procedures observed. For a downloadable copy of the MAR, see:

Description

Volgmer is a backdoor Trojan designed to provide covert access to a compromised system. Since at least 2013, HIDDEN COBRA actors have been observed using Volgmer malware in the wild to target the government, financial, automotive, and media industries.

It is suspected that spear phishing is the primary delivery mechanism for Volgmer infections; however, HIDDEN COBRA actors use a suite of custom tools, some of which could also be used to initially compromise a system. Therefore, it is possible that additional HIDDEN COBRA malware may be present on network infrastructure compromised with Volgmer

The U.S. Government has analyzed Volgmer’s infrastructure and have identified it on systems using both dynamic and static IP addresses. At least 94 static IP addresses were identified, as well as dynamic IP addresses registered across various countries. The greatest concentrations of dynamic IPs addresses are identified below by approximate percentage:

  • India (772 IPs) 25.4 percent
  • Iran (373 IPs) 12.3 percent
  • Pakistan (343 IPs) 11.3 percent
  • Saudi Arabia (182 IPs) 6 percent
  • Taiwan (169 IPs) 5.6 percent
  • Thailand (140 IPs) 4.6 percent
  • Sri Lanka (121 IPs) 4 percent
  • China (82 IPs, including Hong Kong (12)) 2.7 percent
  • Vietnam (80 IPs) 2.6 percent
  • Indonesia (68 IPs) 2.2 percent
  • Russia (68 IPs) 2.2 percent

Technical Details

As a backdoor Trojan, Volgmer has several capabilities including: gathering system information, updating service registry keys, downloading and uploading files, executing commands, terminating processes, and listing directories. In one of the samples received for analysis, the US-CERT Code Analysis Team observed botnet controller functionality.

Volgmer payloads have been observed in 32-bit form as either executables or dynamic-link library (.dll) files. The malware uses a custom binary protocol to beacon back to the command and control (C2) server, often via TCP port 8080 or 8088, with some payloads implementing Secure Socket Layer (SSL) encryption to obfuscate communications.

Malicious actors commonly maintain persistence on a victim’s system by installing the malware-as-a-service. Volgmer queries the system and randomly selects a service in which to install a copy of itself. The malware then overwrites the ServiceDLL entry in the selected service’s registry entry. In some cases, HIDDEN COBRA actors give the created service a pseudo-random name that may be composed of various hardcoded words.

Detection and Response

This alert’s IOC files provide HIDDEN COBRA indicators related to Volgmer. DHS and FBI recommend that network administrators review the information provided, identify whether any of the provided IP addresses fall within their organizations’ allocated IP address space, and—if found—take necessary measures to remove the malware.

When reviewing network perimeter logs for the IP addresses, organizations may find instances of these IP addresses attempting to connect to their systems. Upon reviewing the traffic from these IP addresses, system owners may find some traffic relates to malicious activity and some traffic relates to legitimate activity.

Network Signatures and Host-Based Rules

This section contains network signatures and host-based rules that can be used to detect malicious activity associated with HIDDEN COBRA actors. Although created using a comprehensive vetting process, the possibility of false positives always remains. These signatures and rules should be used to supplement analysis and should not be used as a sole source of attributing this activity to HIDDEN COBRA actors.

Network Signatures

alert tcp any any -> any any (msg:"Malformed_UA"; content:"User-Agent: Mozillar/"; depth:500; sid:99999999;)

___________________________________________________________________________________________________

YARA Rules

rule volgmer
{
meta:
description = "Malformed User Agent"
strings:
$s = "Mozillar/"
condition:
(uint16(0) == 0x5A4D and uint16(uint32(0x3c)) == 0x4550) and $s
}

Impact

A successful network intrusion can have severe impacts, particularly if the compromise becomes public and sensitive information is exposed. Possible impacts include

  • temporary or permanent loss of sensitive or proprietary information,
  • disruption to regular operations,
  • financial losses incurred to restore systems and files, and
  • potential harm to an organization’s reputation.

Solution

Mitigation Strategies

DHS recommends that users and administrators use the following best practices as preventive measures to protect their computer networks:

  • Use application whitelisting to help prevent malicious software and unapproved programs from running. Application whitelisting is one of the best security strategies as it allows only specified programs to run, while blocking all others, including malicious software.
  • Keep operating systems and software up-to-date with the latest patches. Vulnerable applications and operating systems are the target of most attacks. Patching with the latest updates greatly reduces the number of exploitable entry points available to an attacker.
  • Maintain up-to-date antivirus software, and scan all software downloaded from the Internet before executing.
  • Restrict users’ abilities (permissions) to install and run unwanted software applications, and apply the principle of “least privilege” to all systems and services. Restricting these privileges may prevent malware from running or limit its capability to spread through the network.
  • Avoid enabling macros from email attachments. If a user opens the attachment and enables macros, embedded code will execute the malware on the machine. For enterprises or organizations, it may be best to block email messages with attachments from suspicious sources. For information on safely handling email attachments, see Recognizing and Avoiding Email Scams. Follow safe practices when browsing the web. See Good Security Habits and Safeguarding Your Data for additional details.
  • Do not follow unsolicited web links in emails. See Avoiding Social Engineering and Phishing Attacks for more information.

Response to Unauthorized Network Access