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Threat Spotlight: Amadey Bot Targets Non-Russian Users

Threat Spotlight: Amadey Bot Targets Non-Russian Users

Amadey is a simple Trojan bot first discovered in October of 2018[1]. It is primarily used for collecting information on a victim's environment, though it can also deliver other malware.

A major infection vector for Amadey are exploit kits such as RigEK and Fallout EK[2]. During our monitoring, we also observed this Trojan being delivered via AZORult Infostealer[3] on February 23rd to March 1st, and April 18th to June 5th. The sample hash values were not changed frequently. Recently, TA505 used Amadey for their campaign in April 2019[4].

This technical blog reveals the detailed behavior of Amadey and examines its AZORult campaign. It focuses on the latest sample (DE8A40568834EAF2F84A352D91D4EA1BB3081407867B12F33358ABD262DC7182) which was actively spread for about a month.

Technical Analysis

Obfuscation

Amadey possesses decode logic as seen in Figure 1. It obfuscates strings like domain name, dll file names, API names, antivirus (AV) vendor names, and so on. For example, “94 D6 CD CF 99 DA AD 92 CF CD 98 D7 96 AA A1 D6 AA A1 D6 94 C6 A6 CF” (embedded in this malware file) decodes to the command and control (C2) domain name: ashleywalkerfuns[.]com.



Figure 1: Amadey’s decode routine

Installation

When run, Amadey looks for antivirus products installed on the victim machine (see Table 1). Next, it copies itself to “C:\ProgramData\44b36f0e13\” as “vnren.exe” and then executes that file before terminating the original process. The “ProgramData” subfolder name is hardcoded in the binary and it can vary from sample to sample:

AV Product

Code

AVAST Software

0x1

Avira

0x2

Kaspersky Lab

0x3

ESET

0x4

Panda Security

0x5

Doctor Web

0x6

AVG

0x7

360TotalSecurity

0x8

BitDefender

0x9

Norton

0xA

Sophos

0xB

Comodo

0xC

Table 1: AV product names and codes

If Amadey finds Norton (0xA) or Sophos (0xB) AV software installed on the victim machine, it does not drop itself under the %PROGRAMDATA% directory (see Figure 2): 



Figure 2: Amadey does not drop itself if it finds Norton or Sophos

Persistence

For persistence, Amadey changes the Startup folder to the one containing “vnren.exe”. It overwrites the registry keys to change the Startup folder, as shown in Figure 3:


Figure 3: Amadey overwrites the Startup folder for its persistence

It also checks for installed antivirus products. If it finds 360TotalSecurity, as shown in Figure 4, it does not overwrite the registry key:



Figure 4: Amadey does not establish its persistence when it finds 360 Total Security

C2 Communication

Table 2 shows the parameters and their values which Amadey uses for its POST requests:

Key

Value

id

Identification. Computed based on Volume Serial Number.

vs

Amadey version (1.09 for these samples)

ar

If victim user has administrative privilege, the value is 1. Otherwise, it is 0.

bi

“1” for 64 bit. “0” for 32 bit.

lv

Install additional malware if the value is 0.

os

OS version. (e.g., Windows 7 is 9).

av

If there is no antivirus product, it is 0. Otherwise, it is assigned to a number in Table 1.

pc

Computer name from GetComputerNameA

un

User name from GetUserNameA

Table 2: POST parameters of Amadey

Amadey sends the parameters in plaintext to the C2 servers every 60 seconds (see Figure 5):


Figure 5: Request example

The C2 server returns a list of URLs to remote malware files. Amadey downloads and runs the remote files to further infect the host machine with additional malware (see Figure 6):


Figure 6: Response example

During our investigation, we found the following login page shown by the C2 server (see Figure 7):


Figure 7: A live Amadey C2 login page

Amadey C2 Tool

The source code for Amadey’s administrator tool is on Github[5]. We set the tool up in our test environment to investigate its functionality and found:

  • Statistical information of victim machines (Figure 8)
  • A list of infected machines (Figure 9)
  • Task management of additional malware installation (Figure 10)
       ◦  The C2 tool will not run any tasks or install any additional malware if the victim machine is in Russia (Figure 11):


Figure 8: Statistics information


Figure 9: All victim information


Figure 10: Task creation


Figure 11: The C2 tool will not run any tasks against victims in Russia
(NOTE: Some lines of code are removed)

Amadey Campaign via AZORult

In 2019, BlackBerry Cylance discovered two Amadey campaigns involving AZORult Infostealer. The first ran between February 23rd to March 1st (Table 3), the second from April 18th and June 5th (Table 4). We suspect these campaigns were led by the same attacker based on following profile:

  • All of them used the same version (v1.09)
  • Remote files names start with “ama”
  • All of them included Amadey dropping itself as “vnren.exe”
     

SHA256

URL

Date

b23c8e970c3d7ecd762e15f084f0675c
b011fc2afe38e7763db25810d6997adf

hXXp://www[.]llambrich[.]com/ama[.]exe

Feb. 23 2019 - Feb. 24 2019

e1efb7e182cb91f2061fd02bffebb5e4
b9a011d176a6f46e26fc5b881a09044f

hXXp://motorgalicia[.]es/amad[.]exe

Feb. 25 2019 - Mar. 1 2019

Table 3: Amadey campaign from otsosukadzima[.]com (an AZORult C2 server)

SHA256 (Amadey)

URL

Dates

5f581635e962eae615827376b609d34a
cd6b01d0572e51f2fe7b858d82119509

hXXp://2[.]59[.]42[.]63/amad_orj_pr[.]exe

Apr. 18 2019

3df371b9daed1a30dd89dabd88608f64
b000b6dddff3a958bf0edbd756640600

hXXp://2[.]59[.]42[.]63/amad_yo[.]exe

Apr. 18 2019 - Apr. 20 2019

de8a40568834eaf2f84a352d91d4ea1b
b3081407867b12f33358abd262dc7182

hXXp://ashleywalkerfuns[.]com/ama_orj_pr[.]exe

Apr. 25 2019 - May. 21 2019, May. 28 2019 – Jun. 5 2019

Table 4: Amadey campaign from kadzimagenius[.]com (an AZORult C2 server)

Conclusion

Amadey is a new bot family spread by AZORult infostealer. The source code analysis of its C2 tool revealed that it does not download additional malware if victims are in Russia.

BlackBerry Cylance uses artificial intelligence-based agents trained for threat detection on millions of both safe and unsafe files. Our automated security agents block Amadey based on countless file attributes and malicious behaviors instead of relying on a specific file signature. BlackBerry Cylance, which offers a predictive advantage over zero-day threats, is trained on and effective against both new and legacy cyberattacks.

If you are a BlackBerry Cylance customer using CylancePROTECT®, you are protected from Amadey by our machine learning models. 

For more information visit  https://www.cylance.com.
 

Citations:

[1] https://pastebin.com/U415KmF3
[2] https://www.malware-traffic-analysis.net/2019/02/28/index.html
[3] https://threatvector.cylance.com/en_us/home/threat-spotlight-analyzing-azorult-infostealer-malware.html
[4] https://medium.com/@1ZRR4H/ta505-intensifica-ciberataques-a-chile-y-latinoam%C3%A9rica-con-flawedammy-9fb92c2f0552
[5] https://github.com/prsecurity/amadey

Masaki Kasuya

About Masaki Kasuya

Senior Threat Researcher at BlackBerry Cylance, Japan

Masaki Kasaki started his professional career as Security Engineer at a large e-commerce company and earned practical experience in malware analysis, penetration testing, incident response, and corporate IT security. His Ph.D. dissertation sought how to stimulate stealthy malware’s behavior. While he was Ph.D. student, he received student paper award and student presentation award. He holds SANS GREM, GCFA, GCIH, GCIA and GMOB.