Ransomware Data Recovery

Staines Data Recovery: The UK’s No.1 Ransomware Decryption & Data Recovery Specialists

For 25 years, Staines Data Recovery has been the UK’s leading expert in combating ransomware attacks. We provide forensic-grade data recovery services for all systems encrypted by ransomware, from individual laptops and desktops to complex enterprise RAID servers and network-attached storage (NAS). Our dedicated cyber-forensics lab employs a multi-faceted arsenal of techniques to recover your data without capitulating to criminal demands.

Common Ransomware Strains We Decrypt:
WannaCry, LockBit, REvil (Sodinokibi), Ryuk, Phobos, Dharma, Stop/Djvu, Cerber, CryptoLocker, Maze, Conti, Petya/NotPetya, GandCrab, and many more.

25 Advanced Ransomware Data Recovery Techniques & Our Technical Processes

Ransomware recovery is a forensic discipline that combines deep technical analysis with advanced decryption science. Here are the 25 core techniques we employ in our secure laboratory.

1. Ransomware Strain Identification & Cryptographic Analysis

• Problem: The first critical step is to correctly identify the ransomware variant. Different strains use different encryption algorithms (AES, RSA, Salsa20) and key management schemes. Misidentification leads to wasted effort.

• Technical Recovery Process: We perform static and dynamic analysis of the ransomware binary (if available) or its artifacts. We analyse the encrypted file structure, the ransom note, and the file extensions appended to encrypted files. We cross-reference this with our own database and public databases like No More Ransom’s Crypto Sheriff. We disassemble the malware code to identify the specific cryptographic libraries and functions used, which reveals potential vulnerabilities.

2. Implementation Flaw Exploitation (Weak Random Number Generation)

• Problem: Many ransomware strains, especially older or poorly coded variants, have critical flaws in their random number generation (RNG). If the malware uses a predictable seed (like system time) to generate encryption keys, the keys can be recalculated.

• Technical Recovery Process: We create a forensic image of the infected system’s memory (if available) and storage. We analyse the system logs and memory dumps to determine the exact time of infection with nanosecond precision. Using a known-plaintext attack (e.g., matching an unencrypted file header like PK for ZIP files to its encrypted version), we reverse-engineer the RNG process and brute-force the seed value. Once the seed is known, we can regenerate the encryption keys.

3. Brute-Force Attacks on Weak Encryption Keys

• Problem: Some ransomware uses encryption with insufficient key strength (e.g., a short RSA key or a weak AES key) that is computationally feasible to break through brute force.

• Technical Recovery Process: We deploy a multi-GPU computing cluster running software like Hashcat or custom-built code. For example, if a strain uses a 512-bit RSA key, our cluster can systematically generate and test possible private keys. The attack is optimized using techniques like rainbow tables for symmetric ciphers or Pollard’s rho algorithm for factoring small RSA keys. This process can take from hours to several days, depending on the key length.

4. Known Plaintext Attack & Key Extraction

• Problem: If we have a known unencrypted file and its encrypted counterpart from the same system, we can sometimes derive the encryption key.

• Technical Recovery Process: We scour the system for files that are unlikely to have been modified but were encrypted—such as Windows system files, application binaries, or common PDF headers. By XORing the known plaintext with the ciphertext, we can extract the keystream or directly calculate the symmetric key. This key can then be applied to decrypt all other files encrypted with the same key.

5. Memory Dump Analysis for Residual Keys

• Problem: When a system is infected, the encryption keys exist in plaintext within the computer’s RAM. If the machine was not shut down cleanly (e.g., powered off after the attack), a memory dump or hibernation file (hiberfil.sys) may contain the keys.

• Technical Recovery Process: We create a forensic image of the RAM (if the system is still running) or analyse the hibernation file and pagefile.sys. Using tools like Volatility Framework, we scan the memory dump for cryptographic key patterns, strings from the ransomware process, and large blocks of random data that represent keys in memory. Extracting these keys provides instant decryption capability.

6. Ransomware Decryptor Tool Deployment

• Problem: Cybersecurity companies like Emsisoft, Kaspersky, and Bitdefender often release free decryptors for specific ransomware strains after discovering and exploiting a vulnerability in the malware’s code.

• Technical Recovery Process: We maintain an extensive and up-to-date library of all publicly available decryptors. After positively identifying the strain, we deploy the corresponding tool in a secure, isolated environment. These tools often work by exploiting flaws such as hard-coded keys, poor key generation, or by using a master decryption key obtained by law enforcement or researchers.

7. Shadow Volume Copy (VSS) Restoration

• Problem: Many ransomware strains attempt to delete or encrypt the Volume Shadow Copy Service (VSS) snapshots to prevent easy recovery. However, this process is not always successful or complete.

• Technical Recovery Process: We use forensic tools to scan the drive sectors for the remnants of VSS snapshots. The VSS data structures can often be repaired or manually extracted. Using tools like vssadmin or ShadowExplorer on a raw disk image, we attempt to reconstruct a pre-infection snapshot from the residual data, allowing us to restore files to their unencrypted state.

8. File Signature Carving (Raw Recovery)

• Problem: When files are encrypted, the ransomware typically overwrites the original data. However, in cases of partial encryption or rapid intervention, the original file may still exist in its entirety in the unallocated space or file slack.

• Technical Recovery Process: We perform a deep-sector scan of the entire storage device. Our software carves data based on file headers (signatures) and footers. For example, we search for %PDF- for PDFs, PK for ZIP/JAR files, or JFIF for JPEGs. This recovers the original, unencrypted files that were deleted during the encryption process, before they are overwritten.

9. Backup Recovery from Hidden or Offline Sources

• Problem: Ransomware may encrypt locally connected backups but often misses offline, offsite, or hidden backups.

• Technical Recovery Process: We conduct a full audit of the system and network for backup repositories. This includes checking for previous versions on network drives, disconnected external hard drives, cloud backup snapshots (e.g., AWS S3 Versioning, Azure Backup), and even tape archives. We reconstruct data from these pristine sources.

10. Configuration Analysis & Master Key Derivation

• Problem: Some ransomware strains save the encryption key in a configuration file on the victim’s machine, sometimes obfuscated but not truly encrypted.

• Technical Recovery Process: We search the filesystem for newly created files around the time of infection. These configuration files are reverse-engineered to understand their format. The key or seed is often extracted through simple decoding (Base64, Hex) or by running the ransomware in a sandboxed environment to observe how it writes its configuration.

11. Partially Encrypted File Reconstruction

• Problem: Ransomware may only encrypt the first few megabytes of a large file to speed up the attack. The remainder of the file may be intact.

• Technical Recovery Process: We analyse the encryption pattern by comparing file sizes and examining the ciphertext. For known file types, we can often repair the header and truncate the file to the unencrypted portion. For databases, we can repair the header and salvage most of the records.

12. Database Log File Replay

• Problem: Critical databases (SQL, Oracle) are encrypted. However, database transaction logs may not have been encrypted.

• Technical Recovery Process: We recover the database backup or a pre-encryption version and then replay the transaction logs (.ldf files for SQL Server, redo logs for Oracle) to bring the database back to its state moments before the encryption occurred. This requires expert database administration skills.

13. NTFS MFT (Master File Table) Reconstruction

• Problem: The ransomware encrypts files and corrupts the NTFS MFT, which contains the record of all files on the volume.

• Technical Recovery Process: We parse the raw disk image for copies of the MFT. NTFS keeps a mirror copy of the first few MFT records. We use this to rebuild the file system structure. We then attempt to match the MFT records pointing to encrypted data with carved, unencrypted files from the raw disk, restoring filenames and directory structures.

14. Exploiting Offline Encryption Vulnerabilities

• Problem: Some ransomware uses “offline encryption,” where a unique key is generated for each victim without contacting a Command & Control (C2) server. The decryption key must be embedded within the ransomware or the encrypted system itself.

• Technical Recovery Process: We disassemble the ransomware binary to locate the key generation and storage routines. The key is often hidden within the registry, a hidden file, or appended to the encrypted files themselves. Forensic analysis reveals these locations, allowing for key extraction.

15. Negotiation & Payment as a Last Resort

• Problem: All technical decryption avenues have been exhausted, and the data is of critical, irreplaceable value.

• Technical Recovery Process: We act as an intermediary, using secure channels to negotiate with the attackers to lower the ransom. We verify the attacker’s decryptor works on a sample of our data before any payment is made, using a dedicated, isolated system. We handle the cryptocurrency transaction and application of the decryptor. This is a last-resort option and carries inherent risks.

16. Ransomware Sandboxing & Behavioural Analysis

• Problem: A new, unknown ransomware variant is encountered.

• Technical Recovery Process: We execute the malware in a high-fidelity sandbox environment that mimics a real workstation. We monitor all system calls, file system activity, network traffic, and memory operations. This behavioural analysis reveals how the malware generates keys, encrypts files, and communicates, providing the intelligence needed to develop a custom decryption strategy.

17. Corrupted Ransomware Process Recovery

• Problem: The ransomware process was terminated mid-encryption (e.g., by antivirus software), leaving files partially encrypted and the system in an unstable state.

• Technical Recovery Process: We analyse the half-encrypted files to understand the encryption algorithm and block size. In some cases, the encryption may not have been completed, and the original data may be recoverable by reversing the incomplete encryption steps, especially if the algorithm is a stream cipher like Salsa20.

18. Email and Temporary File Recovery

• Problem: Original files that were attached to emails or stored in temporary folders (Temp, Cache) may have been overlooked by the ransomware.

• Technical Recovery Process: We scan email archives (PST, OST files) and temporary internet folders for copies of critical documents. These locations often contain recent versions of work-in-progress files that can be recovered unencrypted.

19. Firmware-Level Data Access

• Problem: The operating system is corrupted by a bootkit ransomware like Petya, which encrypts the Master Boot Record (MBR).

• Technical Recovery Process: We use hardware-based tools like PC-3000 to directly access the drive sectors, bypassing the corrupted MBR. We can then image the user data area and repair the file system separately, effectively neutering the bootkit component of the attack.

20. RAID Array Reconstruction Post-Attack

• Problem: A ransomware attack on a server encrypts the files across a RAID array, and the array may have been degraded or reconfigured during the incident.

• Technical Recovery Process: We image each physical drive from the array individually. We then perform a virtual RAID reconstruction, carefully determining the correct stripe size, order, and parity rotation. This creates a clean, logical image of the encrypted volume, which we then subject to our standard decryption processes.

21. Cloud Storage Synchronization Recovery

• Problem: A synchronized folder (OneDrive, Dropbox, Google Drive) is encrypted on a local machine, and the encrypted files are synced to the cloud, overwriting the good versions.

• Technical Recovery Process: We immediately work with the cloud provider’s support team to restore the file library to a point-in-time before the synchronization occurred. Most cloud services retain version history for a period, allowing us to roll back to unencrypted versions.

22. Custom Scripting for Unique Strains

• Problem: A ransomware strain has a unique, undocumented encryption method that existing tools cannot handle.

• Technical Recovery Process: Our in-house developers write custom Python or C++ scripts to implement the reverse of the encryption algorithm based on our forensic analysis. This is a painstaking process of testing and validation against known file pairs.

23. Forensic Imaging & Write-Blocking

• Problem: Preserving the evidence and preventing further data loss is the first step in any recovery.

• Technical Recovery Process: Before any action is taken, we create a forensic, bit-for-bit image of the affected storage media using hardware write-blockers. All recovery and analysis work is performed on this image, ensuring the original evidence is never altered—a critical step for potential legal proceedings.

24. Zero-Day Vulnerability Research

• Problem: A sophisticated, new ransomware strain with no known decryptor is identified.

• Technical Recovery Process: Our research team analyses the malware to discover potential zero-day vulnerabilities in its code. This involves advanced reverse engineering, fuzzing, and cryptographic analysis. If a flaw is found, we develop a proof-of-concept decryptor.

25. Post-Recovery Security Forensic Audit

• Problem: After data recovery, it’s crucial to understand how the breach occurred to prevent recurrence.

• Technical Recovery Process: We provide a detailed forensic report outlining the attack vector (e.g., phishing email, RDP vulnerability, unpatched software), the timeline of the infection, and the specific indicators of compromise (IOCs). We recommend security hardening measures to close the vulnerabilities.

Why Choose Staines Data Recovery for Ransomware?

• 25 Years of Forensic Expertise: We combine data recovery with advanced cyber-forensics.

• In-House Decryptor Development: We don’t just rely on public tools; we create our own.

• High-Performance Computing Cluster: For brute-force attacks on weak encryption.

• Forensic Lab with Write-Blocking Hardware: Ensures evidence integrity.

• No Data, No Fee Policy: You only pay if we successfully recover your data.

• Secure & Confidential Service: Your data and situation are handled with utmost discretion.

Contact Staines Data Recovery today for a free forensic diagnostic. Do not pay the ransom until you have spoken to the UK’s leading ransomware recovery specialists.