MAR-10376640-2.v1 – CaddyWiper
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CISA received one unique file for analysis. This file is a malicious 32-bit Windows Portable Executable (PE). During runtime, this malware attempts to overwrite the victim user's files with null bytes. The malware also attempts to overwrite the Master Boot Record of attached drives with null bytes, thereby corrupting them and rendering it impossible for the victim to access the victim's stored data.
For a downloadable copy of IOCs, see: MAR-10376640-2.v1.stix.
Submitted Files (1)
No matches found.
This file is a 32 bit Windows PE that has been identified as a variant of the malware family known as Caddy Wiper. Static analysis of this application indicates its primary purpose is to destroy victim user data. First the malware attempts to enumerate all files in the directory "C:\Users". The malware will then attempt to recursively overwrite files that it can access in this directory with null bytes, effectively "zeroing" the files out.
The malware will then attempt to access drives attached to the target system, starting with the drive "D:\", and recursively "zero" out all the files it can access on those drives too. Finally, the malware attempts to use the API DeviceIoControl to directly access the physical memory of attached drives. If it is able to access these drives, the malware will zero out the first 1920 bytes of the physical drives, effectively wiping its Master Boot Record and corrupting the drive.
Figure 1. - This screenshot illustrates the main structure of the malware. As illustrated, the malware's main purpose is to recursively overwrite victim user's files and physical drives with null bytes.
Figure 2. - Structure that malware uses to build null buffer. This buffer is utilized to overwrite the victim user's target files.
Figure 3. - Malware trying to zero out \\.\PHYSICALDRIVE7
Figure 4. - Malware trying to zero out \\.\PHYSICALDRIVE4
Figure 5. - Malware trying to zero out \\.\PHYSICALDRIVE3
Figure 6. - Malware attempting to zero out first 1920 bytes of a physical drive attached to the target system.
CISA recommends that users and administrators consider using the following best practices to strengthen the security posture of their organization's systems. Any configuration changes should be reviewed by system owners and administrators prior to implementation to avoid unwanted impacts.
Additional information on malware incident prevention and handling can be found in National Institute of Standards and Technology (NIST) Special Publication 800-83, "Guide to Malware Incident Prevention & Handling for Desktops and Laptops".
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What is a MIFR? A Malware Initial Findings Report (MIFR) is intended to provide organizations with malware analysis in a timely manner. In most instances this report will provide initial indicators for computer and network defense. To request additional analysis, please contact CISA and provide information regarding the level of desired analysis.
What is a MAR? A Malware Analysis Report (MAR) is intended to provide organizations with more detailed malware analysis acquired via manual reverse engineering. To request additional analysis, please contact CISA and provide information regarding the level of desired analysis.
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Can I submit malware to CISA? Malware samples can be submitted via three methods:
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April 28, 2022: Initial Version