ELF_DNSAMP.TNK

July 06, 2017
 Analysis by: Julie Anne Cabuhat
 ALIASES:

Linux/MrBlack (AVG), Linux/DDoS-BE (Sophos), Trojan.Linux.Dnsamp (Ikarus)

 PLATFORM:

Linux, UNIX

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet, Via vulnerability

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.

  TECHNICAL DETAILS

File Size:

60,768 bytes

File Type:

ELF

Memory Resident:

Yes

Payload:

Launches DoS/DDoS attacks, Modifies files, Connects to URLs/IPs

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.

This malware arrives via the following means:

Backdoor Routine

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

  • Run command in linux terminal
  • Perform DDOS attacks:
    • TCP Flood
    • SYN Flood
    • UDP Flood
    • STREAM Flood
    • GET Flood
    • DNS Flood
    • UDPK Flood
    • RENT Flood

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • idc3389.{BLOCKED}2.net

Other Details

This Backdoor does the following:

  • It modifies the following files as an autostart technique:
    • /etc/rc.local
    • /etc/rc.d/rc.local
  • By appending the following command:
    • nohup {malware path} /dev/null 2>&1 &

  SOLUTION

Minimum Scan Engine:

9.850

Restart in normal mode and scan your computer with your Trend Micro product for files detected as ELF_DNSAMP.TNK. 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 this Knowledge Base page for more information.


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