Backdoor.Linux.SETAG.RPB

 Analysis by: Patrick Angelo Roderno

 ALIASES:

HEUR:Backdoor.Linux.Ganiw.d (KASPERSKY); Backdoor:Linux/Setag!rfn (MICROSOFT); Linux/Setag.B.Gen trojan (NOD32)

 PLATFORM:

Linux

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware


This Backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It executes commands from a remote malicious user, effectively compromising the affected system.

It connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size:

1,135,000 bytes

File Type:

ELF

Memory Resident:

No

Initial Samples Received Date:

12 Apr 2018

Payload:

Drops files, Connects to URLs/IPs, Steals information

Arrival Details

This Backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Backdoor drops the following copies of itself into the affected system and executes them:

  • /usr/bin/bsd-port/knerl

It creates the following folders:

  • /usr/bin/dpkgd
  • /usr/bin/bsd-port

Backdoor Routine

This Backdoor executes the following commands from a remote malicious user:

  • Initiate DDoS attacks:
    • SYN flood
    • DNS flood
    • ICMP flood
    • UDP flood
    • TCP flood
    • TNS poisoning
    • Challenge Collapsar (CC) attack
  • Stop DDoS attack
  • Execute shell commands

Dropping Routine

This Backdoor drops the following files:

  • /usr/bin/bsd-port/knerl.conf
  • /tmp/notify.file
  • {Malware path}/idus.log
  • {Malware Path}/vga.conf

Information Theft

This Backdoor gathers the following data:

  • OS name
  • OS version
  • CPU clock rate
  • CPU usage
  • Number of CPU cores
  • Network usage
  • RAM size
  • IP address of infected machine

Other Details

This Backdoor connects to the following website to send and receive information:

  • {BLOCKED}163.68
  • {BLOCKED}.192.68
  • {BLOCKED}.213.68
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  • {BLOCKED}10
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  • {BLOCKED}34
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  • {BLOCKED}6.3
  • {BLOCKED}136.10
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  • {BLOCKED}148.39
  • {BLOCKED}26.42
  • {BLOCKED}32.100
  • {BLOCKED}32.103
  • {BLOCKED}32.106
  • {BLOCKED}32.109
  • {BLOCKED}33.52
  • {BLOCKED}33.60
  • {BLOCKED}3.70
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  • {BLOCKED}3.83
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  • {BLOCKED}4.6
  • {BLOCKED}4.9
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  • {BLOCKED}4.15
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  • {BLOCKED}.96.66
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  • {BLOCKED}98.55
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  • {BLOCKED}4.34
  • {BLOCKED}.1
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  • {BLOCKED}110
  • {BLOCKED}1
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  • {BLOCKED}
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  • {BLOCKED}.123
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  • {BLOCKED}07.27
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  • {BLOCKED}03.86
  • {BLOCKED}03.90
  • {BLOCKED}03.98
  • {BLOCKED}92.86
  • {BLOCKED}92.98

It does the following:

  • It adds the following scripts in /etc/rc{1-5}.d/ and /etc/init.d/ to automatically execute itself when the system starts up:
    • /etc/rc{1-5}.d/S97VsystemsshMdt
    • /etc/rc{1-5}.d/S99selinux
    • /etc/init.d/selinux
    • /etc/init.d/VsystemsshMdt
  • replaces the following files with the copy of the malware and stores the original files in /usr/bin/dpkg/:
    • /bin/netstat
    • /bin/lsof
    • /bin/ps
    • /usr/bin/netstat
    • /usr/bin/lsof
    • /usr/bin/ps
    • /usr/sbin/netstat
    • /usr/sbin/lsof
    • /usr/sbin/ps

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.236.04

FIRST VSAPI PATTERN DATE:

15 Jul 2019

VSAPI OPR PATTERN File:

15.237.00

VSAPI OPR PATTERN Date:

16 Jul 2019

Scan your computer with your Trend Micro product to delete files detected as Backdoor.Linux.SETAG.RPB. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check the following Trend Micro Support pages for more information:


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