Technical Breakdown

1. File Extension & Renaming Patterns

Confirmed extension: “.egfg” (lower-case) is appended to every encrypted file
Typical rename pattern:
original-name.ext.id-<8-hex-chars>.[[email protected]].egfg
(The e-mail address in brackets can change between campaigns – earlier waves used “[email protected]”, “[email protected]”, “[email protected]”, etc.)

2. Detection & Outbreak Timeline

First public sightings: 25 Aug 2021 (uploads to ID-Ransomware & VirusTotal)
Peak activity window: Sept 2021 – Jan 2022, with occasional small clusters reported through 2023
Family note: Egfg is simply a re-brand of STOP/Djvu “version 376”; whenever you read “STOP/Djvu” advisories released after Aug 2021 they cover .egfg as well.

3. Primary Attack Vectors

Pirated software & “warez” bundles – most common infection source (>80 % of submissions).
– Fake Adobe Photoshop, Filmora, Vegas Pro, Windows/Office activators (KMS Tools), game cheats.
E-mail attachments – classic invoice/PO/PDF-ZIP combo layered with .iso or .vbs downloader (much less common than STOP’s usual pirated-installer route).
No network worm or RDP爆破 – Egfg does NOT self-spread; each victim is individually compromised by executing the initial downloader.
Exploitation of un-patched OS is irrelevant here; once the downloader runs it simply downloads the final payload from a hard-coded C2 list and executes with the logged-on user’s rights.

Remediation & Recovery Strategies

1. Prevention

Block execution of unsigned or user-downloaded .exe/.msi from %Temp%, %AppData%, Desktop.
Disable Office macros by default; treat incoming .iso, .vbs, .js, .hta as malicious.
Remove local-admin rights from daily-use accounts (Egfg needs write access to C:\ and network shares to do harm).
Patch, but note: Egfg relies on user action, not OS bugs—patching alone will not stop it.
Maintain at least two backups: one offline (air-gapped or immutable S3/Blob bucket) and one standard.
EDR/AV with behaviour-based ransomware shield (Windows Defender ASR rule “Block credential stealing…”, “Block process creations from PSExec & WMI”, etc.).

2. Removal

STEP 1 – Power down the machine (or isolate NIC) to stop encryption of mapped drives.
STEP 2 – Boot into Safe Mode + Networking.
STEP 3 – Use a reputable AV rescue disk (Kaspersky, ESET, Sophos) or simply let Microsoft Defender (fully updated) perform a full scan – it detects STOP/Djvu as Ransom:Win32/Stop.P.
STEP 4 – Delete task-scheduler entries created by the malware:
– Task Scheduler Library\Microsoft\Windows\RandomName (usually a 3-letter name)
– HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run entry pointing to the dropped .exe in %LocalAppData%[random]\
STEP 5 – Clear registry “Startup” and “RunOnce”, reboot normally.
STEP 6 – Install OS updates and the latest agent/AV signatures before restoring data.

3. File Decryption & Recovery

OFFLINE key victims (≈15 %): If the malware could not reach its C2 it fell back to a fixed embedded key. Your ransom note will state “personal ID” that ends with “t1“.
– Upload a pair of original/encrypted files to the Emsisoft STOP-Djvu Decryptor (no-install, free). If the tool reports “Your ID appears to be offline – key available”, follow the wizard to decrypt everything.

ONLINE key victims (≈85 %): Each key is unique; no free decryptor exists. Options are:

Restore from backups after verifying they are intact and disconnected.
Shadow-copy check: vssadmin list shadows; Egfg deletes them but the removal sometimes fails on Win11/Server 2022 – use ShadowExplorer to browse.
File-repair tools (only work on certain file types):
– PhotoRec / TestDisk for lost video/audio if original was contiguous.
– “STOP-Djvu File-Repair” Python scripts for NTFS-compressed .mp3/.ogg headers.
Paying the ransom is NOT recommended – there is no guarantee, and you feed the criminal ecosystem.

4. Other Critical Information

Egfg still uses the classic STOP/Djvu “_readme.txt” ransom note demanding $490 (within 72 h) → $980, payable in BTC to a hard-coded wallet.
The malware selectively skips files located in: \ProgramData\, \AppData\LocalLow\, \Intel, \Windows, \Boot and files with extension .bat, .cmd, .dll, .lnk, .sys to keep the machine bootable.
Network shares are fully encrypted if writeable; ransomware deletes share-level shadow copies via “vssadmin delete shadows /all”.
Every build carries a hard-coded list of ~150 file-extensions to avoid encrypting, which is why system services keep running – helping criminals maximise ransom success while retaining a usable PC.
Because Egfg is not worm-able, immediate isolation of the infected host is usually sufficient to protect the rest of the LAN; re-image that single box and you are done—no need to hunt for lateral movement.

Key Take-away

.egfg is just the 2021-2022 flavour of STOP/Djvu; infection almost always follows a manual install of cracked software. Cut pirated installers out of your environment and you will prevent 80 % of these incidents. For the remaining edge cases, the dual-policies “no local admin” and “multi-layer backup (offline plus immutable)” ensure that even if the worst happens you can simply nuke-and-pave rather than negotiate with extortionists.