Full Report
2024-12-11 • Sublime • Sublime Security • osx.xloader, win.formbook Open article on Malpedia
Analysis Summary
# Tool/Technique: Xloader
## Overview
Xloader is a malware family known for its use in delivering secondary payloads, often utilizing sophisticated social engineering techniques for initial access, such as impersonating legitimate services like SharePoint via links. The article specifically links this delivery mechanism to the potential deployment of Formbook and Xloader variants targeting macOS.
## Technical Details
- Type: Malware family (Loader/Downloader)
- Platform: Windows, macOS (implied by reference to `osx.xloader`)
- Capabilities: Initial access, secondary payload delivery, persistence.
- First Seen: Not explicitly mentioned in the provided text, but delivery methods are recent (2024 context).
## MITRE ATT&CK Mapping
The primary focus is on initial access and execution. Specific mappings depend on the exact stage Xloader is observed, but common loader behaviors map to:
- **Initial Access (TA0001)**
- **T1566 - Phishing**
- T1566.001 - Spearphishing Attachment (If delivered via file)
- T1566.002 - Spearphishing Link (Likely, via SharePoint impersonation)
- **Execution (TA0002)**
- **T1204 - User Execution**
- T1204.002 - Malicious File
## Functionality
### Core Capabilities
- Delivery of secondary malware (e.g., Formbook).
- Exploitation of user trust through impersonation (SharePoint delivery).
### Advanced Features
- Link-based delivery mechanism that leverages social engineering (impersonating SharePoint).
- Variants observed targeting macOS (`osx.xloader`).
## Indicators of Compromise
*Note: The provided text does not contain specific file hashes, registry keys, or C2 indicators for the Xloader deployment discussed.*
- File Hashes: [Not provided in context]
- File Names: [Not provided in context]
- Registry Keys: [Not provided in context]
- Network Indicators: [Not provided in context, but relies on C2 communication post-execution]
- Behavioral Indicators: User clicking on a malicious link leading to the download/execution of the payload, potentially involving interaction with Office document templates or scripts disguised as legitimate files stemming from the SharePoint lure.
## Associated Threat Actors
- [Not explicitly named in the context of the Xloader delivery method discussed, but often associated with financially motivated cybercrime groups.]
## Detection Methods
*Note: General detection methods for loaders are listed, as specific IoCs were absent.*
- Signature-based detection: Signatures may exist for known Xloader file hashes or C2 infrastructure once identified.
- Behavioral detection: Monitoring for unusual file execution following interaction with cloud storage/document links, especially involving scripts or downloaded archives.
- YARA rules: [Not provided in context]
## Mitigation Strategies
- User training emphasizing the scrutiny of links, even those appearing to come from familiar platforms like SharePoint.
- Implementing strict application control to limit the execution of downloaded files.
- Utilizing browser security features and endpoint detection and response (EDR) to monitor execution chains post-click.
## Related Tools/Techniques
- Formbook (mentioned as a potential secondary payload: `win.formbook`).
- Qakbot (mentioned in a related article, indicating similar infection vectors sometimes utilized by other threats).
***
# Tool/Technique: Formbook
## Overview
Formbook is a known information stealer malware family, referenced in conjunction with the Xloader activity, suggesting it may be an intended secondary payload delivered via the SharePoint impersonation chain.
## Technical Details
- Type: Malware family (Infostealer)
- Platform: Windows (implied by `win.formbook`)
- Capabilities: Information theft, credential harvesting.
- First Seen: [Not provided in context]
## MITRE ATT&CK Mapping
Since Formbook is an infostealer, its activities map to Collection and Exfiltration.
- **Collection (TA0009)**
- **T1056 - Input Capture**
- T1056.001 - Keylogging
- **Exfiltration (TA0010)**
- **T1041 - Exfiltration Over C2 Channel**
## Functionality
### Core Capabilities
- Stealing credentials and sensitive information from the compromised host.
### Advanced Features
- [Not detailed in the context, but typically involves clipping data from forms and active windows.]
## Indicators of Compromise
- File Hashes: [Not provided in context]
- File Names: [Not provided in context]
- Registry Keys: [Not provided in context]
- Network Indicators: [Not provided in context, relies on C2 for data exfiltration]
- Behavioral Indicators: Processes attempting to hook into input mechanisms or access credential stores.
## Associated Threat Actors
- [Not explicitly named in the context.]
## Detection Methods
- Signature-based detection for known Formbook variants.
- Behavioral monitoring for processes mimicking file activity, credential access, or unusual network traffic volume outbound.
- YARA rules: [Not provided in context]
## Mitigation Strategies
- Implementing strong endpoint protection that specifically profiles and blocks known infostealer behaviors.
- Using multi-factor authentication (MFA) to mitigate credential theft effectiveness.
## Related Tools/Techniques
- Xloader (as the delivery mechanism).