Remexi

Overview

Executive Summary

Infection Vector and Technical Capabilities

• Covert C2 Communication: Remexi often utilizes legitimate, compromised web servers as proxies for its Command and Control communications. It may also encode its traffic within HTTP POST requests to evade network intrusion detection systems (NIDS).
• Credential Theft and Lateral Movement: The backdoor is used to deploy secondary tools like Mimikatz or customized keyloggers to harvest credentials from the compromised host, enabling lateral movement deeper into the network.
• Data Exfiltration: Remexi provides the attacker with a full remote shell, allowing them to quietly stage, compress, and exfiltrate large databases or archives of sensitive documents back to the attacker-controlled infrastructure.

Threat Assessment

Incident Response and Remediation

• Forensic Triage and Containment: Do not immediately wipe the machine. Isolate the endpoint and any compromised web servers. Incident Response teams must capture volatile memory (RAM) and review IIS/Apache access logs to trace the attacker's lateral movement and identify the exfiltrated data.
• Enterprise-Wide Threat Hunt: The presence of Remexi guarantees the attacker has obtained legitimate administrative credentials. A comprehensive enterprise-wide threat hunt must be initiated to identify all compromised service accounts and secondary backdoors (such as deployed web shells).
• Complete Architecture Review: Remediation requires a full rebuild of the compromised endpoints, a complete reset of the Active Directory environment, and the implementation of strict network segmentation and Web Application Firewalls (WAF) to prevent the initial SQL injection vectors.

Known aliases

Threat reports may refer to this family under multiple names:

• Backdoor.Remexi
• Trojan.Remexi
• APT.Chafer
• APT39

MITRE ATT&CK Techniques

This family has been observed using the following ATT&CK techniques: T1059.003 T1071.001 T1003.001 T1105

Tactical Mitigations

Based on the techniques used by this family, consider the following defensive strategies:

• T1003.001: Monitor for LSASS memory dumping or registry SAM extraction. Enable Credential Guard on Windows systems.
• T1059.003: Restrict execution of Windows Command Shell (cmd.exe) and block unauthorized batch scripts.
• T1071.001: Implement web filtering and SSL/TLS inspection to detect malicious command and control (C2) traffic hiding in HTTP/HTTPS.
• T1105: Implement network intrusion detection systems (NIDS) and host-based firewalls to block unauthorized inbound or outbound file transfers.

Generated Detections (Boilerplate)

These YARA and Sigma rules are auto-generated based on the family name and aliases. They must be heavily tuned before deployment in a production environment.

YARA Rule

rule MALWARE_WIN_REMEXI {
    meta:
        description = "Detects Remexi (trojan)"
        author = "SystemHelpdesk Boilerplate Generator"
        date = "2026-07-06"
    strings:
        $s1 = "remexi" ascii wide nocase
        $s2 = "backdoor.remexi" ascii wide nocase
        $s3 = "trojan.remexi" ascii wide nocase
        $s4 = "apt.chafer" ascii wide nocase
        $s5 = "apt39" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

Sigma Rule

title: Suspicious Remexi Activity
id: eb6c61319e7abfed3e8d3898d7b6d92c
status: experimental
description: Detects generic indicators of the remexi malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*remexi*"
            - "*backdoor.remexi*"
            - "*trojan.remexi*"
            - "*apt.chafer*"
            - "*apt39*"
    condition: selection
level: medium

References & External Analysis

• Search "remexi" on VirusTotal (External Analysis)

Frequently Asked Questions

Related Families (Category: trojan)

Explore other malware families in the same category:

• Driverupdate
• Atomicrat
• Driverdevelop
• Winreg
• Ciadoor

Machine-readable

Get this profile as JSON: https://jordanricky1604-ship-it.github.io/malware-families-catalog/api/remexi.json

Ecosystem & Interactive Environments

This profile is part of the Malware Families Catalog, a public dataset of 2,899 malware families. The catalog is also published across our ecosystem: Hugging Face, Kaggle, Zenodo, Replit, StackBlitz, CodeSandbox, and CodePen.