1. Threat Intelligence Executive Summary
The cybersecurity community has observed a surge in enterprise intrusions orchestrated by the DarkByte ransomware cartel. Emerging as a sophisticated Ransomware-as-a-Service (RaaS) group, DarkByte distinguishes itself through aggressive defensive evasion tactics, notably Bring-Your-Own-Vulnerable-Driver (BYOVD) to terminate kernel-level endpoint detection (EDR) agents, coupled with intermittent ChaCha20-Poly1305 encryption designed to defeat automated backup detection.
– Malware Family: DarkByte Ransomware v4.2
– Primary Encryption Primitive: ChaCha20 (Symmetric) + Curve25519 (Asymmetric Master)
– Defense Evasion: BYOVD (CVE-2019-16098 Micro-Star driver exploitation)
– Exfiltration Tool: Custom Mega.nz and Rclone multithreaded pipelines.
2. Detailed TTP Analysis (MITRE ATT&CK Mapping)
A. Defense Evasion via BYOVD (T1068 / T1562.001)
Modern Endpoint Detection and Response (EDR) platforms run kernel callbacks (via PsSetCreateProcessNotifyRoutine) to block ransomware before encryption begins. To circumvent this, DarkByte drops a legitimately signed, vulnerable third-party kernel driver (e.g. mhyprot2.sys or RTCore64.sys). Utilizing the driver’s unconstrained physical memory read/write primitives, DarkByte zeros out the kernel callback tables of installed security sensors, blinding defenders prior to payload execution.
B. Intermittent Encryption Algorithm
Traditional ransomware encrypts 100% of each targeted file, causing sudden disk I/O spikes that trigger heuristic alarms in storage arrays. DarkByte implements intermittent encryption: it encrypts every alternate 16-byte block or only the file header and footer structures. This renders databases, virtual hard disks (VHD/VMDK), and enterprise documents irreversibly corrupt within seconds, operating at over 10x the speed of full-disk encryption routines.
3. Technical Indicators of Compromise (IoCs)
| TYPE | INDICATOR VALUE | DESCRIPTION |
|---|---|---|
| SHA-256 | e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 |
DarkByte Payload Executable |
| SHA-256 | 48c64d84f885e49c71a39626e2e50cf6097d748f2b7f7300c3b8cb36db163ac9 |
Exploited Vulnerable Driver |
| Registry | HKLMSYSTEMCurrentControlSetServicesRTCore64 |
Driver Persistence Key |
| Ransom Note | README_DARKBYTE_DECRYPT.txt |
Extortion Communication Notice |
4. Enterprise Disaster Recovery & Hardening Recommendations
- Enable Microsoft Vulnerable Driver Blocklist: Enable Hypervisor-Protected Code Integrity (HVCI) and the Windows Kernel Vulnerable Driver Blocklist via Group Policy to prevent unprivileged processes from loading known exploitable drivers.
- Deploy Immutable & Air-Gapped Backups: Maintain offsite, write-once-read-many (WORM) storage architecture with air-gapped retention schedules to guarantee business recovery without ransom compliance.
- Enforce Zero-Trust Network Micro-Segmentation: Strictly prohibit lateral SMBv1/v2/v3 and RPC connectivity between workstation endpoints using local host firewalls.
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