Analysis by: Michelle Morales
 Modified by: Joselyn Canuela
ALIASES:

Linux/DDoS.XOR (AVG), Linux/DDoS-BH (Sophos), ELF:Xorddos-K [Trj] (Avast), HEUR:Trojan-DDoS.Linux.Agent.a (Kaspersky)

 PLATFORM:

Linux

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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.

  TECHNICAL DETAILS

File Size: 662,840 bytes
File Type: ELF
Memory Resident: Yes
Initial Samples Received Date: 25 May 2015

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:

  • /lib/udev/udev
  • /boot/{random characters}

Autostart Technique

This Backdoor drops the following files:

  • /etc/cron.hourly/cron.sh
  • /etc/init.d/rc{random}

Other Details

This Backdoor connects to the following possibly malicious URL:

  • {BLOCKED}.{BLOCKED}.9.228
  • {BLOCKED}.{BLOCKED}.139.244

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 11.334.05
FIRST VSAPI PATTERN DATE: 09 Dec 2014
VSAPI OPR PATTERN File: 11.335.00
VSAPI OPR PATTERN Date: 10 Dec 2014

NOTES:

1. Scan your computer with your Trend Micro product and note files detected as ELF_DDOS.SMLE

2. Identify and terminate the malware process using the noted path in the previous step.

    a. Open the Terminal. Access Applications>Accessories>Terminal or press CTRL + ALT then T.

    b. Type the following in the terminal:

    • ps –A

    c. Look for the detected files and take note of their PIDs. If the detected files are not found to be running, skip step 4.

    d. In the same terminal, enter the following commands for each PIDs:

    • kill {PID}

3. Delete the malware files using the noted path and file name.

In the same Terminal, type the following commands:

  • In the same Terminal, type the following commands:
  • sudo rm -R "/boot/{random 10 characters}"
  • sudo rm -R "/etc/cron.hourly/cron.sh"
  • sudo rm -R "/etc/init.d/rc{random}"
  • sudo rm -R "/lib/udev/udev

Note that the file in /etc/init.d should contain the following content:

  • chkconfig: 12345 9090

    If the files are not present, you may proceed to last step.

    4. Scan your computer with your Trend Micro product to delete files detected as ELF_DDOS.SMLE. 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.


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