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Linux Analysis Report
cats.elf

Overview

General Information

Sample name:	cats.elf
Analysis ID:	1583676
MD5:	3f69f32ced51bb702e37f99b168b7501
SHA1:	6aa20482e18aef7c793ef7b62a9382f0a5faf613
SHA256:	bd4f5d6023050e6c451469ca0e1e777d55d1ef846c8b00cece7c1e29eb422698
Tags:	CobaltStrikeelfmalwareuser-Joker
Infos:

Detection

ConnectBack

Score:	68
Range:	0 - 100
Whitelisted:	false

Signatures

Found malware configuration

Multi AV Scanner detection for submitted file

Yara detected ConnectBack

Machine Learning detection for sample

Detected TCP or UDP traffic on non-standard ports

Sample contains only a LOAD segment without any section mappings

Classification

General Information

Joe Sandbox version:	41.0.0 Charoite
Analysis ID:	1583676
Start date and time:	2025-01-03 10:09:08 +01:00
Joe Sandbox product:	CloudBasic
Overall analysis duration:	0h 4m 16s
Hypervisor based Inspection enabled:	false
Report type:	full
Cookbook file name:	defaultlinuxfilecookbook.jbs
Analysis system description:	Ubuntu Linux 20.04 x64 (Kernel 5.4.0-72, Firefox 91.0, Evince Document Viewer 3.36.10, LibreOffice 6.4.7.2, OpenJDK 11.0.11)
Analysis Mode:	default
Sample name:	cats.elf
Detection:	MAL
Classification:	mal68.troj.linELF@0/0@2/0

Runtime Messages

Command:	/tmp/cats.elf
PID:	5443
Exit Code:	139
Exit Code Info:	SIGSEGV (11) Segmentation fault invalid memory reference
Killed:	False
Standard Output:
Standard Error:

Process Tree

system is lnxubuntu20

cats.elf (PID: 5443, Parent: 5367, MD5: 3f69f32ced51bb702e37f99b168b7501) Arguments: /tmp/cats.elf

cleanup

Malware Threat Intel

Provided by

Name	Description	Attribution	Blogpost URLs	Link
ConnectBack	ConnectBack malware is a type of malicious software designed to establish unauthorized connections from an infected system to a remote server. Once a victim's device is compromised, ConnectBack creates a covert channel for communication, allowing the attacker to remotely control and gather sensitive information from the compromised system.	No Attribution	https://labs.sucuri.net/signatures/malwares/pl-backdoor-connectback-001/	https://malpedia.caad.fkie.fraunhofer.de/details/elf.connectback

Yara Signatures

Initial Sample

Source	Rule	Description	Author	Strings
cats.elf	JoeSecurity_ConnectBack	Yara detected ConnectBack	Joe Security

Memory Dumps

Source	Rule	Description	Author	Strings
5443.1.0000000000400000.0000000000401000.rwx.sdmp	JoeSecurity_ConnectBack	Yara detected ConnectBack	Joe Security

Suricata Signatures

⊘No Suricata rule has matched

Joe Sandbox Signatures

Click to jump to signature section

Show All Signature Results

AV Detection

Found malware configuration

Source: cats.elf

Malware Configuration Extractor: ConnectBack {"C2": "107.173.129.144:4455"}

Multi AV Scanner detection for submitted file

Source: cats.elf	Virustotal: Detection: 42%			Perma Link
Source: cats.elf	ReversingLabs: Detection: 47%

Machine Learning detection for sample

Source: cats.elf

Joe Sandbox ML: detected

Source: global traffic

TCP traffic: 192.168.2.13:42130 -> 107.173.129.144:4455

Source: unknown	TCP traffic detected without corresponding DNS query: 107.173.129.144
Source: unknown	TCP traffic detected without corresponding DNS query: 107.173.129.144
Source: unknown	TCP traffic detected without corresponding DNS query: 107.173.129.144
Source: unknown	TCP traffic detected without corresponding DNS query: 107.173.129.144
Source: unknown	UDP traffic detected without corresponding DNS query: 1.1.1.1
Source: unknown	UDP traffic detected without corresponding DNS query: 1.1.1.1

Source: global traffic

DNS traffic detected: DNS query: daisy.ubuntu.com

Source: LOAD without section mappings

Program segment: 0x400000

Source: classification engine

Classification label: mal68.troj.linELF@0/0@2/0

Stealing of Sensitive Information

Yara detected ConnectBack

Source: Yara match	File source: cats.elf, type: SAMPLE
Source: Yara match	File source: 5443.1.0000000000400000.0000000000401000.rwx.sdmp, type: MEMORY

Remote Access Functionality

Yara detected ConnectBack

Source: Yara match	File source: cats.elf, type: SAMPLE
Source: Yara match	File source: 5443.1.0000000000400000.0000000000401000.rwx.sdmp, type: MEMORY

Mitre Att&ck Matrix

Reconnaissance	Resource Development	Initial Access	Execution	Persistence	Privilege Escalation	Defense Evasion	Credential Access	Discovery	Lateral Movement	Collection	Command and Control	Exfiltration	Impact
Gather Victim Identity Information	Acquire Infrastructure	Valid Accounts	Windows Management Instrumentation	Path Interception	Path Interception	Direct Volume Access	OS Credential Dumping	System Service Discovery	Remote Services	Data from Local System	1 Non-Standard Port	Exfiltration Over Other Network Medium	Abuse Accessibility Features
Credentials	Domains	Default Accounts	Scheduled Task/Job	Boot or Logon Initialization Scripts	Boot or Logon Initialization Scripts	Rootkit	LSASS Memory	Application Window Discovery	Remote Desktop Protocol	Data from Removable Media	1 Non-Application Layer Protocol	Exfiltration Over Bluetooth	Network Denial of Service
Email Addresses	DNS Server	Domain Accounts	At	Logon Script (Windows)	Logon Script (Windows)	Obfuscated Files or Information	Security Account Manager	Query Registry	SMB/Windows Admin Shares	Data from Network Shared Drive	1 Application Layer Protocol	Automated Exfiltration	Data Encrypted for Impact

Malware Configuration

Threatname: ConnectBack

{"C2": "107.173.129.144:4455"}

Behavior Graph

Hide Legend

Legend:

Process
Signature
Created File
DNS/IP Info
Is Dropped
Number of created Files
Is malicious
Internet

Antivirus, Machine Learning and Genetic Malware Detection

Initial Sample

Source	Detection	Scanner	Label	Link
cats.elf	42%	Virustotal		Browse
cats.elf	47%	ReversingLabs	Linux.Backdoor.ConnectBack
cats.elf	100%	Joe Sandbox ML

Dropped Files

⊘No Antivirus matches

Domains

⊘No Antivirus matches

URLs

⊘No Antivirus matches

Domains and IPs

Contacted Domains

Name	IP	Active	Malicious	Antivirus Detection	Reputation
daisy.ubuntu.com	162.213.35.24	true	false		high

World Map of Contacted IPs

No. of IPs < 25%
25% < No. of IPs < 50%
50% < No. of IPs < 75%
75% < No. of IPs

Public IPs

IP	Domain	Country	Flag	ASN	ASN Name	Malicious
107.173.129.144	unknown	United States		36352	AS-COLOCROSSINGUS	true

Joe Sandbox View / Context

IPs

⊘No context

Domains

Match	Associated Sample Name / URL	SHA 256	Detection	Threat Name	Link	Context
daisy.ubuntu.com	powerpc-440fp.elf	Get hash	malicious	Mirai	Browse	162.213.35.25
	x86_64.elf	Get hash	malicious	Mirai	Browse	162.213.35.24
	arm6.elf	Get hash	malicious	Mirai	Browse	162.213.35.25
	armv7l.elf	Get hash	malicious	Mirai	Browse	162.213.35.24
	i586.elf	Get hash	malicious	Mirai	Browse	162.213.35.25
	2.elf	Get hash	malicious	Unknown	Browse	162.213.35.24
	armv6l.elf	Get hash	malicious	Mirai	Browse	162.213.35.25
	armv4l.elf	Get hash	malicious	Mirai	Browse	162.213.35.24
	mipsel.elf	Get hash	malicious	Mirai	Browse	162.213.35.24

ASNs

Match	Associated Sample Name / URL	SHA 256	Detection	Threat Name	Link	Context
AS-COLOCROSSINGUS	DEMONS.sh4.elf	Get hash	malicious	Unknown	Browse	172.245.26.218
	sh4.elf	Get hash	malicious	Unknown	Browse	23.94.37.42
	powerpc.elf	Get hash	malicious	Unknown	Browse	104.168.33.8
	i586.elf	Get hash	malicious	Unknown	Browse	107.175.130.16
	m68k.elf	Get hash	malicious	Unknown	Browse	107.175.130.16
	sparc.elf	Get hash	malicious	Unknown	Browse	104.168.33.8
	i686.elf	Get hash	malicious	Unknown	Browse	107.175.130.16
	x86_64.elf	Get hash	malicious	Unknown	Browse	104.168.33.8
	arm.elf	Get hash	malicious	Unknown	Browse	107.175.130.16
	mips.elf	Get hash	malicious	Unknown	Browse	104.168.33.8

JA3 Fingerprints

⊘No context

Dropped Files

⊘No context

Created / dropped Files

⊘No created / dropped files found

Static File Info

General

File type:	ELF 64-bit LSB executable, x86-64, version 1 (SYSV), statically linked, no section header
Entropy (8bit):	4.276692563343198
TrID:	ELF Executable and Linkable format (Linux) (4029/14) 50.16% ELF Executable and Linkable format (generic) (4004/1) 49.84%
File name:	cats.elf
File size:	250 bytes
MD5:	3f69f32ced51bb702e37f99b168b7501
SHA1:	6aa20482e18aef7c793ef7b62a9382f0a5faf613
SHA256:	bd4f5d6023050e6c451469ca0e1e777d55d1ef846c8b00cece7c1e29eb422698
SHA512:	615a4ecc3e4a6013a1af360e6bd45941cd3759274b509aeb31445ad1a16ccb1f7160448934e393ee300a11f2fdf9df672fcc161197fbf671fa7179490cb6ff8b
SSDEEP:	6:BnX//In8/r1uBxHocmTv+GQ3RQdygg5XJYD:BvwncrAH3mSP532D
TLSH:	99D080330B0A40FADAD4123FB574696CD77B8976574D66311890DC010C0D6146F62C75
File Content Preview:	.ELF..............>.....x.@.....@...................@.8...........................@.......@.............\|...............1.j.X...H..M1.j"AZj.Z..H..xQj.AYPj)X.j._j.^..H..x;H.H....gk...QH..j.Zj*X..YH..y%I..t.Wj#Xj.j.H..H1...YY_H..y.j<Xj._..^j~Z..H..x...

Static ELF Info

ELF header
Class:	ELF64
Data:	2's complement, little endian
Version:	1 (current)
Machine:	Advanced Micro Devices X86-64
Version Number:	0x1
Type:	EXEC (Executable file)
OS/ABI:	UNIX - System V
ABI Version:	0
Entry Point Address:	0x400078
Flags:	0x0
ELF Header Size:	64
Program Header Offset:	64
Program Header Size:	56
Number of Program Headers:	1
Section Header Offset:	0
Section Header Size:	0
Number of Section Headers:	0
Header String Table Index:	0

Program Segments

Type	Offset	Virtual Address	Physical Address	File Size	Memory Size	Entropy	Flags	Flags Description	Align	Prog Interpreter	Section Mappings
LOAD	0x0	0x400000	0x400000	0xfa	0x17c	4.2767	0x7	RWE	0x1000

Network Behavior

Network Port Distribution

TCP Packets

Timestamp	Source Port	Dest Port	Source IP	Dest IP
Jan 3, 2025 10:09:53.559421062 CET	42130	4455	192.168.2.13	107.173.129.144
Jan 3, 2025 10:09:53.564295053 CET	4455	42130	107.173.129.144	192.168.2.13
Jan 3, 2025 10:09:53.564356089 CET	42130	4455	192.168.2.13	107.173.129.144
Jan 3, 2025 10:09:54.980184078 CET	4455	42130	107.173.129.144	192.168.2.13
Jan 3, 2025 10:09:54.983479977 CET	42130	4455	192.168.2.13	107.173.129.144
Jan 3, 2025 10:09:55.135046005 CET	42130	4455	192.168.2.13	107.173.129.144
Jan 3, 2025 10:09:55.139897108 CET	4455	42130	107.173.129.144	192.168.2.13

UDP Packets

Timestamp	Source Port	Dest Port	Source IP	Dest IP
Jan 3, 2025 10:09:55.664217949 CET	55451	53	192.168.2.13	1.1.1.1
Jan 3, 2025 10:09:55.664293051 CET	52056	53	192.168.2.13	1.1.1.1
Jan 3, 2025 10:09:55.670914888 CET	53	52056	1.1.1.1	192.168.2.13
Jan 3, 2025 10:09:55.671869993 CET	53	55451	1.1.1.1	192.168.2.13

DNS Queries

Timestamp	Source IP	Dest IP	Trans ID	OP Code	Name	Type	Class	DNS over HTTPS
Jan 3, 2025 10:09:55.664217949 CET	192.168.2.13	1.1.1.1	0xd95a	Standard query (0)	daisy.ubuntu.com	A (IP address)	IN (0x0001)	false
Jan 3, 2025 10:09:55.664293051 CET	192.168.2.13	1.1.1.1	0x56f4	Standard query (0)	daisy.ubuntu.com	28	IN (0x0001)	false

DNS Answers

Timestamp	Source IP	Dest IP	Trans ID	Reply Code	Name	CName	Address	Type	Class	DNS over HTTPS
Jan 3, 2025 10:09:55.671869993 CET	1.1.1.1	192.168.2.13	0xd95a	No error (0)	daisy.ubuntu.com		162.213.35.24	A (IP address)	IN (0x0001)	false
Jan 3, 2025 10:09:55.671869993 CET	1.1.1.1	192.168.2.13	0xd95a	No error (0)	daisy.ubuntu.com		162.213.35.25	A (IP address)	IN (0x0001)	false

System Behavior

Analysis Process: cats.elf PID: 5443, Parent PID: 5367

General

Start time (UTC):	09:09:53
Start date (UTC):	03/01/2025
Path:	/tmp/cats.elf
Arguments:	/tmp/cats.elf
File size:	250 bytes
MD5 hash:	3f69f32ced51bb702e37f99b168b7501

Description:	Adversaries may communicate using a protocol and port pairing that are typically not associated. For example, HTTPS over port 8088or port 587as opposed to the traditional port 443. Adversaries may make changes to the standard port used by a protocol to bypass filtering or muddle analysis/parsing of network data.
Tactics:	Command and Control
Data Sources:	Network Traffic: Network Traffic Content, Network Traffic: Network Traffic Flow
Platforms:	Linux, macOS, Windows
Url:	Open detailed description by Mitre

Description:	Adversaries may use an OSI non-application layer protocol for communication between host and C2 server or among infected hosts within a network. The list of possible protocols is extensive.Specific examples include use of network layer protocols, such as the Internet Control Message Protocol (ICMP), transport layer protocols, such as the User Datagram Protocol (UDP), session layer protocols, such as Socket Secure (SOCKS), as well as redirected/tunneled protocols, such as Serial over LAN (SOL).
Tactics:	Command and Control
Data Sources:	Network Traffic: Network Traffic Content, Network Traffic: Network Traffic Flow
Platforms:	Linux, macOS, Network, Windows
Url:	Open detailed description by Mitre

Description:	Adversaries may communicate using OSI application layer protocols to avoid detection/network filtering by blending in with existing traffic. Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server.
Tactics:	Command and Control
Data Sources:	Network Traffic: Network Traffic Content, Network Traffic: Network Traffic Flow
Platforms:	Linux, macOS, Windows
Url:	Open detailed description by Mitre

Behavior Section

Behavior Chronological

Disassembly

Uncategorized

Graph

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Warning!

Linux Analysis Report cats.elf

Overview

General Information

Detection

Signatures

Classification

General Information

Runtime Messages

Process Tree

Malware Threat Intel

Yara Signatures

Initial Sample

Memory Dumps

Suricata Signatures

Joe Sandbox Signatures

AV Detection

Networking

System Summary

Stealing of Sensitive Information

Remote Access Functionality

Mitre Att&ck Matrix

Malware Configuration

Threatname: ConnectBack

Behavior Graph

Antivirus, Machine Learning and Genetic Malware Detection

Initial Sample

Dropped Files

Domains

URLs

Domains and IPs

Contacted Domains

World Map of Contacted IPs

Public IPs

Joe Sandbox View / Context

IPs

Domains

ASNs

JA3 Fingerprints

Dropped Files

Created / dropped Files

Static File Info

General

Static ELF Info

ELF header

Program Segments

Network Behavior

Network Port Distribution

TCP Packets

UDP Packets

DNS Queries

DNS Answers

System Behavior

Analysis Process: cats.elf PID: 5443, Parent PID: 5367

General

Chronological Activities

Linux Analysis Report
cats.elf