Best Practices When Using AVG Decryption Tool to Defeat SZFLocker Ransomware

How to Use AVG Decryption Tool for SZFLocker: Step-by-Step GuideSZFLocker is a ransomware family that encrypts victims’ files and demands payment for the decryption key. AVG (now part of Avast/Gen) has released decryption tools for various ransomware strains when researchers recover keys or develop reliable methods to reverse the encryption. This guide explains how to safely use the AVG decryption tool for SZFLocker, from preparing your environment to running the tool and verifying recovered files.

Important safety notes before you begin

• Do not pay the ransom. Paying funds the attackers and does not guarantee file recovery.
• Work on copies. Always operate on copies of infected disks or files; never run recovery directly on original data.
• Scan for active threats. Remove any remaining ransomware executables or persistence mechanisms before attempting decryption.
• Check tool applicability. Decryption tools only work for specific variants and infection circumstances; confirm the tool supports your SZFLocker variant.

1) Confirm the infection and collect evidence

1. Identify common SZFLocker indicators:
   • Encrypted files with a distinctive extension (note the exact extension).
   • Ransom note files (TXT, HTML or similar) left in folders.
   • Filenames or header markers that match known SZFLocker patterns.
2. Preserve a copy of the encrypted drive (disk image) using a trusted imaging tool (e.g., dd, FTK Imager) so you can always revert if needed.
3. Save the ransom note and several encrypted and original filenames for analysis. These help determine variant and whether available keys/decrypters apply.

2) Obtain the correct AVG decryption tool

1. Go to AVG’s official support or decryption tool page (or the “No More Ransom” project which aggregates official decryptors). Verify digital signatures or checksums when available.
2. Download the specific SZFLocker decryption package. Often the file will be labeled for the ransomware family and a version or variant identifier.

3) Prepare a safe working environment

1. Use an isolated, offline workstation (or a virtual machine) to avoid re-infection or accidental network spread.
2. Install a clean copy of Windows (or the OS the tool requires) and ensure the system has no other malicious software.
3. Create a working folder with:
   • A copy of encrypted files (or mount your disk image read-only).
   • The ransom note and any sample encrypted files for testing.
4. Ensure you have enough disk space to store both original encrypted copies and decrypted outputs.

4) Run antivirus scans and remove remnants

1. Run a full scan with AVG (or another reputable AV) to remove active ransomware executables, scheduled tasks, registry persistence, and other artifacts.
2. If the malware used network shares or cloud storage, disconnect and examine those locations; do not reconnect until the environment is clean.

5) Identify key requirements and inputs

1. Some decryptors need additional inputs:
   • A matching pair of an encrypted file and its original unencrypted version (a known-plaintext attack).
   • The ransom note or a sample encrypted filename to auto-detect the variant.
2. Check the tool’s README or instruction file for required parameters (e.g., a folder path, key file, or sample file).

6) Execute the AVG decryption tool

1. Read the included instructions carefully. Typical steps:
   • Launch the decrypter executable (often named something like “avg_decrypter_SZFLocker.exe”).
   • Point it to a test folder containing a few encrypted files and, if required, their corresponding originals.
   • Provide any sample files or keys the tool requests.
2. Run in “test” or “dry-run” mode first if available. This verifies the tool’s detection and prevents accidental corruption.
3. Monitor progress and logs. If the tool reports an unsupported variant or errors, stop and gather logs for troubleshooting.

7) Verify decrypted files

1. Compare decrypted files with known-good originals (if available) or open them to confirm readability.
2. Check file sizes, timestamps, and contents to ensure decryption succeeded and files are intact.
3. If some files fail, note patterns (file types, sizes, locations) and consult the tool’s documentation or support resources.

8) Recover remaining data and clean up

1. Once confident the decryptor works reliably on test files, decrypt the full dataset in batches, keeping a backup of encrypted copies until the process completes successfully.
2. Re-scan the system for malware after decryption to ensure no reinfection.
3. Restore files to their original locations and verify application compatibility.

9) If the AVG tool fails

• Confirm you downloaded the correct version and that the SZFLocker variant is supported.
• Try alternative reputable decryptors (No More Ransom, other major AV vendors) — different teams may have tools for other variants.
• Consider professional data recovery services; forensic specialists can sometimes reconstruct files when decryption tools fail.
• If no decryption is possible, rely on backups and rebuilding systems rather than paying attackers.

10) Post-recovery actions and prevention

• Patch operating systems, applications, and remote-access services exploited during the attack.
• Improve backups: maintain offline, versioned backups and test restores regularly.
• Apply endpoint protection, EDR, phishing defenses, and network segmentation to reduce future risk.
• Educate users on phishing and suspicious attachments.

Troubleshooting quick checklist

• Tool reports “unsupported variant” — verify sample ransom note and file extension match the tool’s supported list.
• Decryption completes but files are corrupted — try decrypting smaller batches, check for incomplete copies, or consult logs.
• Errors about missing keys — the variant may require a private key not available publicly.

If you want, provide: (a) one encrypted sample filename and the ransom note text, or (b) a screenshot of the tool’s error log — I can help diagnose whether this AVG decryptor applies to your SZFLocker variant.