XorDDOS Strikes Hard Once Again

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In recent years, XorDDOS has become a notorious malware family that has been found targeting Linux systems.
The latest attack, originating from China, showcases the malware’s new and improved capabilities.
The attack has been successful in infecting numerous systems, compromising their security, and stealing data.
Attack Phases:
The XorDDOS malware has evolved significantly, employing a range of techniques to infect and persist on the targeted system.
The attack phases include:
1.
Sample persists itself using System V runlevels: The malware first attempts to persist itself using the System V runlevels, which are a standard initialization system used by Linux distributions.
By doing so, the malware ensures that it is automatically started during the boot process.
2.
Sample tries to persist itself using cron: The malware also tries to persist itself using cron, a time-based job scheduler in Unix-like operating systems.
It creates two shell script files, “/etc/cron.hourly/cqqbnzzu.sh” and “/etc/cron.hourly/obidhyb.sh”, which are executed every hour.
3.
Writes shell script files to disk: The malware writes shell script files to disk, which it uses to execute its various attack phases.
4.
Sample deletes itself: The malware deletes itself after completing its attack phases to avoid detection.
5.
Encode data using XOR: The malware encodes its data using XOR to obfuscate its malicious code.
6.
Encrypt data using RC4 PRGA: The malware encrypts its data using RC4 PRGA, a symmetric key stream cipher, to prevent detection by security software.
7.
Contain obfuscated stackstrings: The malware contains obfuscated stackstrings, which makes it difficult to analyze.
8.
Enumerates processes within the “proc” file system: The malware enumerates processes within the “proc” file system to gather information about the system.
9.
Reads system information from the proc file system: The malware reads system information from the proc file system to determine the system’s kernel version.
10.
May try to detect the virtual machine to hinder analysis: The malware may try to detect the virtual machine to hinder analysis.
VM artifact strings found in memory can reveal that the system is a virtual machine.
11.
Uses the “uname” system call to query kernel version information: The malware uses the “uname” system call to query kernel version information, which may be used to evade detection.
12.
Get number of processors: The malware gets the number of processors on the system.
13.
Downloads files from webservers via HTTP: The malware downloads files from webservers via HTTP to carry out its malicious activities.
IOCs:
The attack’s IOCs include several IP addresses, file hashes, and related malware families.
The following are the IOCs:
http://203.205.254[.]157:80/lib.xlsx
http://qq[.]com/lib.xlsx
61.177.172.[32]
ea40ecec0b30982fbb1662e67f97f0e9d6f43d2d587f2f588525fae683abea73 (ELF file)
Related samples:
Intezer: https://analyze.intezer.com/analyses/80cb27cb-c901-4850-8d9f-42943fdd990a/sub/1bb60d9f-5e64-4d34-9c44-acbe45a682ea/related-samples
Related families:
https://analyze.intezer.com/analyses/80cb27cb-c901-4850-8d9f-42943fdd990a/sub/1bb60d9f-5e64-4d34-9c44-acbe45a682ea/code-reuse
Strings reuse patternt: F”4YA/A
Conclusion:
XorDDOS continues to be a major threat to Linux systems.
The latest attack showcases the malware’s sophisticated techniques to evade detection and persist on the targeted system.
It is crucial to take measures to secure Linux systems and prevent attacks from compromising sensitive data.