MAR-10135536-3 - HIDDEN COBRA RAT/Worm

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Description

This submission includes four unique files. The first is an installer for additional malware: a Remote Access Trojan (RAT) and a malicious Dynamic Link Library (DLL) that functions as a Server Message Block (SMB) Worm. The fourth file is another SMB worm in the form of a Windows 32-bit executable.

Both SMB worms attempt to spread locally and to random IP addresses on the public Internet by attempting to brute force vulnerable systems using a built-in list of common passwords. The RAT included with the SMB worm provides the attacker with the ability to deliver additional malware, run local commands, and exfiltrate data.

As of May 31, 2018, this report has been updated to correct the email addresses used by Wmmvsvc.dll (ea46ed5aed900cd9f01156a1cd446cbb3e10191f9f980e9f710ea1c20440c781).

• MAR-10135536-3.stix

Emails (2)

misswang8107@gmail.com

redhat@gmail.com

Submitted Files (4)

077d9e0e12357d27f7f0c336239e961a7049971446f7a3f10268d9439ef67885 (4731CBAEE7ACA37B596E38690160A7...)

a1c483b0ee740291b91b11e18dd05f0a460127acfc19d47b446d11cd0e26d717 (scardprv.dll)

ea46ed5aed900cd9f01156a1cd446cbb3e10191f9f980e9f710ea1c20440c781 (Wmmvsvc.dll)

fe7d35d19af5f5ae2939457a06868754b8bdd022e1ff5bdbe4e7c135c48f9a16 (298775B04A166FF4B8FBD3609E7169...)

077d9e0e12357d27f7f0c336239e961a7049971446f7a3f10268d9439ef67885

Tags

backdoortrojanworm

Details

Antivirus

Yara Rules

ssdeep Matches

No matches found.

PE Metadata

PE Sections

Packers/Compilers/Cryptors

Process List

Relationships

Description

This 32-bit Windows executable file drops two malicious applications.

The first (a1c483b0ee740291b91b11e18dd05f0a460127acfc19d47b446d11cd0e26d717) is a fully functioning RAT.

The second application (ea46ed5aed900cd9f01156a1cd446cbb3e10191f9f980e9f710ea1c20440c781) is a SMB worm that will spread to local subnets and external networks.

a1c483b0ee740291b91b11e18dd05f0a460127acfc19d47b446d11cd0e26d717

Tags

backdoorbottrojanworm

Details

Antivirus

Yara Rules

ssdeep Matches

No matches found.

PE Metadata

PE Sections

Packers/Compilers/Cryptors

Relationships

Description

This 32-bit Windows DLL is written to disk and then loaded by the file "4731CBAEE7ACA37B596E38690160A749".

This malware has been identified as a RAT, providing a remote actor with the ability to exfiltrate data, drop and run secondary payloads, and provide proxy capabilities on a compromised Windows device. The malware binds to port 443 and listens for incoming connections from a remote operator, using the Rivest Cipher 4 (RC4) encryption algorithm to protect communications with its Command and Control (C2).

The malware also creates a log entry in a file named “mssscardprv.ax”, located in the %WINDIR%\system32 folder. The log entry includes the victim's Internet Protocol (IP) address, host name, and current system time.

ea46ed5aed900cd9f01156a1cd446cbb3e10191f9f980e9f710ea1c20440c781

Tags

backdoorbottrojanworm

Details

Antivirus

Yara Rules

ssdeep Matches

No matches found.

PE Metadata

PE Sections

Packers/Compilers/Cryptors

Relationships

Description

This file is a malicious 32-bit Windows DLL that is written to disk then loaded by the file "4731CBAEE7ACA37B596E38690160A749".

When executed, the DLL attempts to contact all of the Internet Protocol (IP) addresses on the victim's local subnet. If the malware is able to connect to these IP addresses, it will attempt to gain unauthorized access via the SMB protocol on port 445 using a brute-force password attack. The malware contains an embedded password list consisting of commonly used passwords and generates random external IP addresses, which it attempts to attack.

If the malware successfully gains access to another system, it will send an email containing the system's IP address, hostname, username, and password to the following address:

--Begin email address--
misswang8107@gmail.com
--End email address--

The email will appear to be from the following address (Refer to Figure 1):

--Begin email address--
redhat@gmail.com
--End email address--

The malware uses the victim's system folder to create a shared folder named "adnim$" by running the following commands via a remotely run service:

--Begin commands utilized to create SMB share--
cmd.exe /q /c net share adnim$=%SystemRoot%
cmd.exe /q /c net share adnim$=%%SystemRoot%% /GRANT:%s,FULL
--End commands utilized to create SMB share--

The malware will then copy itself to newly created shared folder as a file named "mssscardprv.ax". After copying the malware to the new system it then runs the file on the victim system using a malicious service. The adnim$ share will then be deleted from the remote system using the following command:

--Begin command used to delete share--
'cmd.exe /q /c net share adnim$ /delete'
--End command used to delete share--

The malware determines if Remote Desktop Protocol (RDP) is enabled by attempting to connect to port 3389. If it is able to connect to this port, the malware will report RDP is available on the compromised system. This information is provided to the operator using the malicious email address provided earlier.

This malware can communicate with the RAT identified as "scardprv.dll" (4613f51087f01715bf9132c704aea2c2). The communication is protected with the Rivest Cipher 4 (RC4) encryption protocol. When attempting to propagate, the malware uses the following three usernames combined with a password brute-force attack:

--Begin malicious usernames used by SMB worm--
Administrateur
Administrador
Administrator
--End malicious usernames used by SMB worm--

Although the malware uses numerous embedded passwords in its brute force attacks, within our environment the malware consistently used the following "Lan Manager Response" in its SMB attacks:

--Begin static Lan Manager response--
8C15084FA541079A000000000000000000
--End static Lan Manager response--

This hexadecimal value may be useful in detecting this worm as it communicates over port 445 and attempts to spread. Specifically, when the malware attempts to run a remote service to create the "adnim$" share, the following network traffic is generated:

--Begin network signature--
ASCII: cmd.exe /q /c net share adnim$=%SystemRoot% /GRANT:Administrator,FULL
HEX: 636D642E657865202F71202F63206E65742073686172652061646E696D243D2553797374656D526F6F7425202F4752414E543A41646D696E6973747261746F722C46554C4C
--End network signature--

Screenshots

fe7d35d19af5f5ae2939457a06868754b8bdd022e1ff5bdbe4e7c135c48f9a16

Tags

backdoortrojanworm

Details

Antivirus

Yara Rules

ssdeep Matches

No matches found.

PE Metadata

PE Sections

Packers/Compilers/Cryptors

Process List

Description

This file is a malicious 32-bit Windows executable file designed to scan the local network and the Internet for machines that are accessible and have open SMB ports. Once the malware gains access to a remote machine, it will deliver a malicious payload. This file accepts the following command-line arguments for execution:

--Begin arguments--
-i ==> Create service
-u ==> Control and delete service
-s ==> Start service
-r ==> Run not as a service
-k ==> ControlService
--End arguments--


When executed with the "-i" argument, the malware installs and executes itself as the following service:

--Begin service information--
ServiceName = "RdpCertification"
DisplayName = "Remote Desktop Certification Services"
DesiredAccess = SERVICE_ALL_ACCESS
ServiceType = SERVICE_WIN32_OWN_PROCESS|SERVICE_INTERACTIVE_PROCESS
StartType = SERVICE_AUTO_START
BinaryPathName = "%current directory%\298775B04A166FF4B8FBD3609E716945.exe"
--End service information--


The malware creates a mutual exclusion (Mutex) object named "PlatFormSDK20150201", then generates a list of IP addresses using a domain generation algorithm (DGA). The DGA uses the system time in the algorithm to create the list of IP addresses.

It generates network traffic over Transmission Control Protocol (TCP) ports 80 and 445 via the victims' IP addresses and the generated IP addresses.

Sample HTTP request:

--Begin HTTP request--
OPTIONS / HTTP/1.1
translate: f
User-Agent: Microsoft-WebDAV-MiniRedir/5.1.2600
Host: 159.154.100.0
Content-Length: 0
Connection: Keep-Alive
--End HTTP request--

Once successfully connected to other Windows hosts or the generated IP addresses using port 445, the malware attempts to use a hard-coded list of passwords for SMB connections. If the password is correctly guessed, a file share is established. The malware uses the following methods to access shares on the remote systems:

To gain access to remote systems it uses ($IPC) share via “\\remote system IP\$IPC”
It checks for existing shares by using “\\hostname\adnim$\system32”

It will create a new share named "adnim$" using the following command:

--Begin new share command--
“cmd.exe /q /c net share adnim$=%SystemRoot%”
“cmd.exe /q /c net share adnim$=%%SystemRoot%% /GRANT:%s,FULL”
--End new share command—


Once a file share is successfully established, the malware uploads a copy of a payload "C:\WINDOWS\TEMP\TMP1.tmp" and installs it as a service. The malware payload that is uploaded and then run on the newly infected host was not available at the time of analysis.

The remote network share is removed after infection using the following command:

--Begin command--
“cmd.exe /q /c net share adnim$ /delete”
--End command--

Once the payload has been uploaded and executed, the malware uses Simple Mail Transfer Protocol (SMTP) to send collected data. The data provides infection status to a remote operator.

Displayed below are the domain names of the service providers used to send data:

--Begin SMTP domain information--
"www.hotmail.com"
--End SMTP domain information--

Displayed is the structure of the email sent:

--Begin email structure format--
SUBJECT: %s%s%s
TO: Joana <%s>%s
FROM: <%s>%s
DATA%s
RCPT TO: <%s>%s
MAIL FROM: <%s>%s
AUTH LOGIN%s
HELO %s%s
--End email structure format--


Displayed is a list of brute force passwords used to establish connections:

--Begin brute force password--
!@#$
!@#$%
!@#$%^
!@#$%^&
!@#$%^&*
!@#$%^&*()
"KGS!@#$%"
0000
00000
000000
00000000
1111
11111
111111
11111111
11122212
1212
121212
123123
123321
1234
12345
123456
1234567
12345678
123456789
123456^%$#@!
1234qwer
123abc
123asd
123qwe
1313
1q2w3e
1q2w3e4r
1qaz2wsx
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
4321
54321
654321
6969
666666
7777
8888
88888
888888
8888888
88888888
Admin
abc123
abc@123
abcd
admin
admin123
admin!23
admin!@#
administrator
administrador
asdf
asdfg
asdfgh
asdf123
asdf!23
baseball
backup
blank
cisco
compaq
control
computer
cookie123
database
dbpassword
db1234
default
dell
enable
fish
foobar
gateway
guest
golf
harley
home
iloveyou
internet
letmein
Login
login
love
manager
oracle
owner
pass
passwd
password
p@ssword
password1
password!
passw0rd
Password1
pa55w0rd
pw123
q1w2e3
q1w2e3r4
q1w2e3r4t5
q1w2e3r4t5y6
qazwsx
qazwsxedc
qwer
qwert
qwerty
!QAZxsw2
root
secret
server
sqlexec
shadow
super
sybase
temp
temp123
test
test!
test1
test123
test!23
winxp
win2000
win2003
Welcome1
Welcome123
xxxx
yxcv
zxcv
Administrator
Admin
--End brute force password--

redhat@gmail.com

Details

Relationships

misswang8107@gmail.com

Details

Relationships

NCCIC would like to remind users and administrators to 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 thumbdrives, external drives, CDs, etc.).
• Scan all software downloaded from the Internet prior to executing.
• Maintain situational awareness of the latest threats and implement appropriate ACLs.

Additional information on malware incident prevention and handling can be found in NIST's Special Publication 800-83, Guide to Malware Incident Prevention & Handling for Desktops and Laptops.

• 1-888-282-0870
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• us-cert@dhs.sgov.gov (SIPRNET)
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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 NCCIC 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 NCCIC at 1-888-282-0870 or soc@us-cert.gov.

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

• Web: https://malware.us-cert.gov
• E-Mail: submit@malware.us-cert.gov
• FTP: ftp.malware.us-cert.gov (anonymous)

NCCIC 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 the NCCIC/US-CERT homepage at www.us-cert.gov.