Full Report
FortiGuard Labs analyzes the botnet campaign, a Mirai variant targeting global sectors. Learn its tactics, C2 methods, and Fortinet defenses.
Analysis Summary
# Tool/Technique: Gayfemboy Botnet Malware (Mirai Variant)
## Overview
The "Gayfemboy" is a botnet campaign observed by FortiGuard Labs, derived from the Mirai malware family. It is actively exploiting vulnerabilities in various IoT and networking devices (DrayTek, TP-Link, Raisecom, Cisco ISE) globally to compromise systems, potentially for inclusion in a botnet, evidenced by the presence of XMRig coin miners in download payloads.
## Technical Details
- Type: Malware family (Botnet/IoT Malware)
- Platform: Primarily Linux-based IoT/Network Devices (DrayTek, TP-Link, Raisecom, Cisco ISE) running various architectures (ARM, MIPS, PPC, x86-64).
- Capabilities: Exploiting known vulnerabilities for initial access, sophisticated evasion techniques, process inspection, and deployment of secondary payloads (e.g., coin miners).
- First Seen: The campaign resurfaced in July 2025, according to the report timeline.
## MITRE ATT&CK Mapping
As this is a novel, evolving malware, specific mappings are inferred from described behaviors:
- **TA0001 - Initial Access**
- T1190 - Exploit Public-Facing Application (Targeting vulnerabilities in DrayTek, TP-Link, etc.)
- **TA0003 - Persistence**
- (Inferred, common for botnets)
- **TA0005 - Defense Evasion**
- T1027 - Obfuscated Files or Information (Modified UPX header)
- **TA0004 - Privilege Escalation**
- (Inferred through exploitation of vulnerable network devices)
- **TA0011 - Command and Control**
- (Inferred via botnet structure, though C2 details are not fully elaborated in the provided excerpt)
## Functionality
### Core Capabilities
* **Exploitation:** Leverages multiple disclosed vulnerabilities in vendor products (DrayTek, TP-Link, Raisecom, Cisco ISE) for remote compromise.
* **Architecture Specific Naming:** Avoids traditional Mirai/Gafgyt naming conventions; assigns specific file names per Linux architecture (e.g., `a4le`, `xale`, `mbe`) instead of architecture names as extensions.
* **Process Inventory:** Scans `/proc/[PID]/exe` paths across all running processes to map the local execution environment.
* **Payload Delivery:** Utilizes distinct downloader scripts named after product types (e.g., "asus," "zyxel") which execute the malware and potentially secondary payloads like XMRig coin miners.
### Advanced Features
* **Anti-Unpacking Evasion:** The malware is packed with UPX but modifies the standard UPX magic header (`UPX!`) to a non-printable hexadecimal sequence (`10 F0 00 00`), specifically to evade signature-based unpacking detection.
* **Process Name Concealment:** Inspects running processes for telltale keywords like `(deleted)`, `/tmp/.`, `/bot.`, and specific bot agent names (`dvrlocker`, `/.ai`) to identify and potentially target or avoid other malware instances.
* **Execution Trigger:** Displays the string "twinks :3" upon successful execution (potential debugging or identification marker).
## Indicators of Compromise
* File Hashes:
* `90ce16246f484503bd0670c597ea102679d86b`
* `737a795bfb19059062ee2f0a7b2ea0e88283413e76d1b796782423006f3b2cdf`
* `7fda54c9a489fea2dc8f7248d7bf72e1e356e47366478c0d5f4ba421dddf4ab7`
* *(Many other hashes listed in the article excerpt)*
* File Names: Varies widely based on architecture (e.g., `a4le` for ARM, `xale1` for x86-64). Downloader scripts are named after product brands (e.g., `asus`, `zyxel`).
* Registry Keys: Not applicable (Linux/IoT focused).
* Network Indicators:
* Initial Attack Source: `87[.]121[.]84[.]34` (defanged)
* Download Host: `220[.]158[.]234[.]135` (defanged)
* Behavioral Indicators:
* Scanning of `/proc/[PID]/exe` directories.
* Execution exhibiting the "twinks :3" string.
* Deployment of XMRig coin miners observed post-download.
## Associated Threat Actors
* Initially disclosed by an unnamed Chinese cybersecurity firm. The current iteration is tracked by FortiGuard Labs in a global botnet campaign. The name "Gayfemboy" is the identifier used for this specific strain/campaign.
## Detection Methods
* Signature-based detection: Detection signature tailored for the modified UPX header structure (`10 F0 00 00`).
* Behavioral detection: Monitoring for the execution flow that involves scanning the `/proc` filesystem for executable paths and the deployment of cryptocurrency mining software (XMRig).
* YARA rules: Not explicitly provided in the excerpt, but YARA rules could be developed targeting unique strings or the anti-unpacking header modification.
## Mitigation Strategies
* **Patching:** Immediately patch vulnerable systems (DrayTek Vigor2960, TP-Link Archer AX21, Raisecom MSG series, Cisco ISE) to versions released after the disclosed vulnerabilities were fixed.
* **Network Segmentation:** Limit exposure of critical network appliances to the internet where possible.
* **Application Monitoring:** Deploy application whitelisting or monitoring known to detect suspicious process execution or unusual access to the `/proc` filesystem structure.
## Related Tools/Techniques
* **Mirai:** The core structure is derived from the Mirai botnet.
* **Gafgyt:** Mentioned as a related variant that typically uses different file naming conventions.
* **XMRig:** Observed secondary payload, a common monolithic cryptominer used by various botnets.