Full Report
2025-06-12 • Symantec • Carbon Black, Threat Hunter Team • win.fog Open article on Malpedia
Analysis Summary
# Tool/Technique: Fog Ransomware
## Overview
Fog Ransomware is a specific strain of malware deployed in a recent attack that utilized an unusual combination of tools and frameworks. The primary purpose of this malware is typically to encrypt files on compromised systems and demand a ransom for their decryption.
## Technical Details
- Type: Malware family (Ransomware)
- Platform: Windows (Inferred from `win.fog` reference, typical for mainstream ransomware)
- Capabilities: File encryption, ransom negotiation.
- First Seen: Information not explicitly provided in the context snippet, but linked to a report dated 2025-06-12.
## MITRE ATT&CK Mapping
*Note: Since the context is limited, MITRE mappings are inferred based on generic ransomware behavior.*
- TA0011 - Collection
- T1005 - Data from Local System
- TA0040 - Impact
- T1486 - Data Encrypted for Impact
## Functionality
### Core Capabilities
- Encrypting user and system files to deny access to data.
- Likely drops a ransom note or modifies the desktop background.
### Advanced Features
- The description highlights an "Unusual Toolset Used," suggesting proprietary or non-standard auxiliary tools were leveraged alongside the ransomware payload for initial access, staging, or defense evasion.
## Indicators of Compromise
- File Hashes: [Not provided in the context]
- File Names: [Not provided in the context]
- Registry Keys: [Not provided in the context]
- Network Indicators: [Not provided in the context]
- Behavioral Indicators: [Not provided in the context]
## Associated Threat Actors
- Details not explicitly mentioned, but associated with the report authors/sources: Carbon Black and Threat Hunter Team (Symantec).
## Detection Methods
- Since the toolset is described as "unusual," signatures targeting known ransomware families may be ineffective initially. Generic behavioral monitoring for file system modification (high volume encryption activity) is crucial.
- Signature-based detection: Requires sample analysis.
- Behavioral detection: Monitoring for suspicious file access patterns associated with encryption.
- YARA rules: [Not provided in the context]
## Mitigation Strategies
- Regular, offline/immutable backups to ensure recovery without paying the ransom.
- Principle of Least Privilege to limit the scope of file encryption.
- Application Control to prevent execution of unknown executables commonly dropped by ransomware.
## Related Tools/Techniques
- Related to other Windows ransomware families accessing systems via unknown vectors implied by the "Unusual Toolset" description.