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Crutch

Crutch is a backdoor designed for document theft that has been used by Turla since at least 2015.[1]

ID: S0538
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Type: MALWARE
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Platforms: Windows
Version: 1.0
Created: 04 December 2020
Last Modified: 22 December 2020
Enterprise Layer
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Techniques Used

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

Crutch has conducted C2 communications with a Dropbox account using the HTTP API.[1]
Enterprise T1560 .001 Archive Collected Data: Archive via Utility

Crutch has used the WinRAR utility to compress and encrypt stolen files.[1]
Enterprise T1119 Automated Collection

Crutch can automatically monitor removable drives in a loop and copy interesting files.[1]
Enterprise T1020 Automated Exfiltration

Crutch has automatically exfiltrated stolen files to Dropbox.[1]
Enterprise T1005 Data from Local System

Crutch can exfiltrate files from compromised systems.[1]
Enterprise T1025 Data from Removable Media

Crutch can monitor removable drives and exfiltrate files matching a given extension list.[1]
Enterprise T1074 .001 Data Staged: Local Data Staging

Crutch has staged stolen files in the C:\AMD\Temp directory.[1]
Enterprise T1041 Exfiltration Over C2 Channel

Crutch can exfiltrate data over the primary C2 channel (Dropbox HTTP API).[1]
Enterprise T1567 .002 Exfiltration Over Web Service: Exfiltration to Cloud Storage

Crutch has exfiltrated stolen data to Dropbox.[1]
Enterprise T1008 Fallback Channels

Crutch has used a hardcoded GitHub repository as a fallback channel.[1]
Enterprise T1574 .001 Hijack Execution Flow: DLL Search Order Hijacking

Crutch can persist via DLL search order hijacking on Google Chrome, Mozilla Firefox, or Microsoft OneDrive.[1]
Enterprise T1036 .004 Masquerading: Masquerade Task or Service

Crutch has established persistence with a scheduled task impersonating the Outlook item finder.[1]
Enterprise T1120 Peripheral Device Discovery

Crutch can monitor for removable drives being plugged into the compromised machine.[1]
Enterprise T1053 .005 Scheduled Task/Job: Scheduled Task

Crutch has the ability to persist using scheduled tasks.[1]
Enterprise T1102 .002 Web Service: Bidirectional Communication

Crutch can use Dropbox to receive commands and upload stolen data.[1]

Groups That Use This Software

ID Name References
G0010 Turla

[1][2]

References

  1. Faou, M. (2020, December 2). Turla Crutch: Keeping the “back door” open. Retrieved December 4, 2020.
  1. Cisco Talos. (2021, September 21). TinyTurla - Turla deploys new malware to keep a secret backdoor on victim machines. Retrieved December 2, 2021.