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Remexi

Remexi is a Windows-based Trojan that was developed in the C programming language.[1]

ID: S0375
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Type: MALWARE
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Platforms: Windows
Version: 1.1
Created: 17 April 2019
Last Modified: 30 March 2020
Enterprise Layer
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Techniques Used

Domain ID Name Use
Enterprise T1071 .001 Application Layer Protocol: Web Protocols

Remexi uses BITSAdmin to communicate with the C2 server over HTTP.[1]
Enterprise T1010 Application Window Discovery

Remexi has a command to capture active windows on the machine and retrieve window titles.[1]
Enterprise T1560 Archive Collected Data

Remexi encrypts and adds all gathered browser data into files for upload to C2.[1]
Enterprise T1547 .001 Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder

Remexi utilizes Run Registry keys in the HKLM hive as a persistence mechanism.[1]
.004 Boot or Logon Autostart Execution: Winlogon Helper DLL

Remexi achieves persistence using Userinit by adding the Registry key HKLM\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\Userinit.[1]
Enterprise T1115 Clipboard Data

Remexi collects text from the clipboard.[1]
Enterprise T1059 .003 Command and Scripting Interpreter: Windows Command Shell

Remexi silently executes received commands with cmd.exe.[1]
.005 Command and Scripting Interpreter: Visual Basic

Remexi uses AutoIt and VBS scripts throughout its execution process.[1]
Enterprise T1140 Deobfuscate/Decode Files or Information

Remexi decrypts the configuration data using XOR with 25-character keys.[1]
Enterprise T1041 Exfiltration Over C2 Channel

Remexi performs exfiltration over BITSAdmin, which is also used for the C2 channel.[1]
Enterprise T1083 File and Directory Discovery

Remexi searches for files on the system. [1]
Enterprise T1056 .001 Input Capture: Keylogging

Remexi gathers and exfiltrates keystrokes from the machine.[1]
Enterprise T1027 Obfuscated Files or Information

Remexi obfuscates its configuration data with XOR.[1]
Enterprise T1053 .005 Scheduled Task/Job: Scheduled Task

Remexi utilizes scheduled tasks as a persistence mechanism.[1]
Enterprise T1113 Screen Capture

Remexi takes screenshots of windows of interest.[1]
Enterprise T1047 Windows Management Instrumentation

Remexi executes received commands with wmic.exe (for WMI commands). [1]

Groups That Use This Software

ID Name References
G0087 APT39

[2][1][3]

References

  1. Legezo, D. (2019, January 30). Chafer used Remexi malware to spy on Iran-based foreign diplomatic entities. Retrieved April 17, 2019.
  2. Symantec Security Response. (2015, December 7). Iran-based attackers use back door threats to spy on Middle Eastern targets. Retrieved April 17, 2019.
  1. Symantec. (2018, February 28). Chafer: Latest Attacks Reveal Heightened Ambitions. Retrieved May 22, 2020.