akira-ransomware-reverse - Comprehensive reverse engineering analysis of Akir

项目说明

Akira Ransomware: Complete Technical Analysis

A comprehensi engineering analysis of the Akira ransomware

!Analysis Status
!Documentation
!Diagrams
!

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Executi

This repository contains a comprehensi analysis of the Akira ransomware , conducted through deep reverse engineering using Ghidra, Frida, and x64dbg. The analysis spans 8,930+ lines of technical documentation with 69 professional diagrams co every aspect of the malware's operation.

Key Findings

Critical Identified:
1. Nonce Reuse - Same ChaCha20 key+nonce used across multiple files per thread, enabling XOR-based plaintext recovery
2. Case-Sensitivity Bypass - Blacklist filtering uses case-sensiti, allowing "WINDOWS" vs "Windows" bypass
3. Weak RNG Implementation - Time-based random number generation with 30-60% recovery success rate in

Attack Characteristics:

Detection Windows:

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Repository Structure

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Documentation Index

Core Technical Analysis (Comprehensi)

#### Primary Documentation
1. Binary & Static Analysis (2,000+ lines)
- Binary characteristics, PE structure, imports/exports
- Startup sequence and initialization
- Main function architecture and control flow
- Command-line interface and configuration
- Complete function reference (25+ functions)

2. Cryptography Analysis (3,000+ lines)
- ChaCha20 stream cipher implementation
- RSA-2048 public key analysis
- Session key generation and RNG analysis
- CRITICAL: Weak time-based RNG (CVSS 9.1)
- Attack and decryption feasibility
- Complete cryptographic function reference (22+ functions)

3. Threading & Execution (3,000+ lines)
- Dual thread pool architecture (ASIO library)
- Thread allocation algorithm (30/10/60 split)
- Synchronization mechanisms (critical sections, condition )
- Producer-consumer pattern and task queue system
- Dri and directory tra
- File filtering system (5 extensions, 11 directories, 13 processes)
- CRITICAL: Restart Manager process termination
- Complete threading function reference (40+ functions)

4. Encryption Strategy & Operational Model (3,000+ lines)
- Three encryption modes (Full, Part, Spot)
- 512-byte footer structure (byte-accurate)
- CRITICAL: NO network communication (fire-and-forget design)
- registration model (pre-configured credentials)
- Data exfiltration strategy (separate tools)
- Anti-analysis assessment (minimal e)
- Post-encryption actions (shadow copy deletion only)
- Decryption mechanism analysis
- Recovery possibilities (30-60% for VMs with weak RNG exploit)
- Complete attack timeline (T-30 days to T+7 days)
- Comparison to ransomware families (LockBit, BlackCat, Conti, REvil)
- Detection and pre strategies (YARA + EDR rules)
- Incident response guidance

#### Supplementary Documentation

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Key Technical Details

Architecture O

Execution Phases:
1. Logging Initialization (T+0.000s - T+0.012s) - 12ms
2. CLI Argument Parsing (T+0.012s - T+0.024s) - 12ms
3. Argument (T+0.024s - T+0.071s) - 47ms
4. Subsystem Initialization (T+0.071s - T+0.116s) - 45ms ← RSA key parsing bottleneck
5. Dri (T+0.116s - T+0.166s) - 50ms
6. Encryption Campaign (T+0.166s - T+3000s) - 99.9% of total time
7. Post-Encryption (T+3000s - T+3002s) - Shadow copy deletion + ransom note

Threading Model:

Cryptographic Implementation

ChaCha20 Custom :

RSA-2048 Key Encryption:

File Footer Structure (512 bytes @ 0x1400b7010):

Performance Metrics

Throughput Analysis (50 GB dataset):

Resource Utilization:

Performance Breakdown:

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Details

1. Nonce Reuse (CRITICAL)

Se: CRITICAL
CVE: N/A (malware)
Impact: Plaintext recovery via XOR attack

Description:
Each worker thread generates a single ChaCha20 key+nonce pair and reuses it for all files processed by that thread. Since ChaCha20 is a stream cipher, reusing the same key+nonce for multiple plaintexts allows XOR-based recovery.

Attack :

Exploitation:

Remediation for Defenders:

2. Case-Sensitivity Blacklist Bypass (HIGH)

Se: HIGH
Impact: System file encryption possible

Description:
Directory blacklist uses case-sensiti comparison. Windows filesystem is case-insensitive, but blacklist filtering is case-sensitive.

Bypass Example:

Impact:

Detection:

3. Weak RNG - Time-Based Seeding (MEDIUM)

Se: MEDIUM
Impact: Partial key recovery possible (30-60% success in VMs)

Description:
Random number generation uses time-based seeding, making it partially predictable in controlled en (VMs, sandboxes).

Exploitation:

Remediation:

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Detection & Defense

YARA Rules

See yara-rules/ directory for detection signatures.

Key Indicators:

EDR Detection Opportunities

Critical Detection Windows:

Window 1: Pre-Encryption (T+0-10s) - HIGHEST PRIORITY

Window 2: Early Encryption (T+10-300s) - HIGH PRIORITY

Window 3: Mid Encryption (T+300-1500s) - MEDIUM PRIORITY

Window 4: Post-Encryption (T+3000s) - LOW PRIORITY

Beha Indicators

File System:

Process Behavior:

Performance:

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Indicators of Compromise (IOCs)

File Indicators

Memory Indicators

Beha Indicators

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Mitigation Strategies

Pre Measures

1. Real-Time Beha Detection:
- Monitor for rapid thread creation (8-16 threads within 10 seconds)
- Alert on sustained 91% CPU usage + 100% disk saturation
- Detect mass file renaming patterns (.akira extension)
- Block PowerShell shadow copy deletion commands

2. File System Protection:
- Enable Controlled Folder Access (Windows Defender)
- Implement honeypot files in monitored directories
- Enable VSS ( Shadow Copy Service) with frequent snapshots
- Maintain offline backups (3-2-1 backup strategy)

3. Network Segmentation:
- Isolate critical file servers from workstations
- Implement least-pri access controls
- Monitor lateral mo attempts

4. Endpoint Hardening:
- Disable PowerShell for non-administrati
- Implement application whitelisting
- Enable tamper protection for security tools

Response Procedures

If Akira Detected (T+0-10s):
1. Immediately terminate process (100% recovery possible)
2. Isolate affected system from network
3. Preser dump for forensic analysis
4. Restore from last known-good backup

If Encryption In Progress (T+10-300s):
1. Terminate process immediately (70% recovery possible)
2. Identify encrypted files (.akira extension)
3. Restore encrypted files from backup
4. Attempt nonce reuse exploitation for identical RSA footer files

If Encryption Complete (T+3000s+):
1. Block shadow copy deletion (if not already executed)
2. Preserve for recovery
3. Restore from backups (do not pay ransom)
4. Conduct forensic analysis to determine entry

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Research Methodology

Tools & Techniques

Static Analysis:

Dynamic Analysis:

Analysis Techniques:

Analysis Metrics

Time In:

Documentation Output:

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Contributing

This is a completed research project. However, contributions are welcome for:

Please open an issue or pull request with your contributions.

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Disclaimer

IMPORTANT: This analysis is provided for educational, research, and defensi purposes only. The information contained in this repository is intended to help security professionals:

DO NOT:

The authors and contributors are not responsible for any misuse of this information.

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License

This research and documentation are released under the MIT License for educational and defensi purposes.

See LICENSE file for details.

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Authors & Acknowledgments

Research Organization: MottaSec
Analysis Date: 2025-11-08
Tools: Ghidra, Python, Custom analysis scripts

Acknowledgments:

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Contact & References

For questions or collaboration:

Related Research:

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Last Updated: 2025-11-08
Repository Status: Complete Analysis
: 1.0

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Quick Na

Comprehensi Documents

| Document | Lines | Co | Key Findings |
|----------|-------|----------|-------------|
| Binary & Static Analysis | 2,000+ | Phases 1-2 | PE structure, startup sequence, main architecture, CLI |
| Cryptography Analysis | 3,000+ | Phase 3 | ChaCha20, RSA-2048, Weak RNG (CVSS 9.1), attack |
| Threading & Execution | 3,000+ | Phases 4-5 | ASIO pools, 30/10/60 split, file filtering, Restart Manager |
| Encryption Strategy | 3,000+ | Phases 6-10 | 3 modes, 512B footer, NO network, recovery (30-60% VMs) |

Supplementary Resources

| Resource | Type | Purpose |
|----------|------|---------|
| | Report | C, exploitation details |
| IOCs | Intelligence | File, network, beha indicators |
| YARA Rules | Detection | Signature-based detection rules |
| Analysis Scripts | Tools | Python utilities for analysis |

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🔒 Akira Ransomware Analysis - Complete Technical Documentation

项目信息

开发语言：Python

Star 数：7

技术要点

该项目属于防护思路方向的开源资源，代码结构清晰，适合安全研究人员学习参考。项目围绕Comprehensive reverse engineering analysis of Akira ransomware: cryptography, threading architecture, vulnerabilities (CVSS 9.1), IOCs, and detection strategies展开，提供了可运行的实现，对理解相关安全机制、工具原理与攻防技术具有较高的研究价值。

从技术实现角度看，此类项目的核心在于对底层原理的深入理解与工程化落地。开发者在研究过程中可以结合官方文档与社区讨论，梳理项目的初始化流程、核心模块职责与数据流转，逐步掌握其中的技术细节与设计思路。

使用与学习建议

1. 下载源码压缩包，解压到本地环境。

2. 根据项目类型准备对应的运行环境与依赖。

3. 按照 README 中的步骤完成配置与部署。

4. 在隔离的测试环境中运行验证，避免影响生产系统。

免责声明

本资源来源于开源社区，仅供安全研究、技术学习与合法授权范围内的攻防演练使用，请勿用于任何非法或侵害他人权益的用途。使用本项目产生的一切后果由使用者自行承担。