Hvad er GDCB-filformatet?
En .gdcb-fil er et dokument, foto eller en anden fil, der blev krypteret af version 1 af GandCrab ransomware. Når malwaren kører, koder den filens indhold og tilføjer .GDCB til slutningen af navnet, så budget.xlsx bliver til budget.xlsx.GDCB. Den placerer også en løsesumsnote kaldet GDCB-DECRYPT.txt i hver berørt mappe.
GandCrab dukkede op i slutningen af januar 2018 og spredte sig via RIG exploit-kittet. Version 1 krypterede filer med AES-256 og beskyttede nøglen med en RSA-2048 offentlig nøgle, og krævede derefter betaling i Dash-kryptovaluta via en Tor-side. Kun version 1 brugte .GDCB; senere versioner skiftede til filendelserne .CRAB og .KRAB.
Sikkerhed og tryghed
RISIKO: HIGHA .gdcb file itself is inert encrypted data, but its presence means a machine was compromised by GandCrab ransomware. The malware executable that created it is dangerous and may still be active, so disconnect the device, remove the infection with an anti-malware tool, and only then decrypt. Never pay the Dash ransom; a free decryptor exists for GandCrab v1.
Formatdetaljer
kort fortaltProgrammer der åbner GDCB-filer
Windows4 apps
Bitdefender GandCrab Decryption Tool
Gratis Run the free decryptor to reverse GandCrab v1 encryption and restore the original file from a .gdcb copy; it removes the .GDCB extension once decryption succeeds.
No More Ransom Crypto Sheriff
Gratis Upload a sample .gdcb file and the GDCB-DECRYPT.txt note to confirm the GandCrab variant and get pointed to the correct free decryptor.
Malwarebytes
Freemium Scan and remove the active GandCrab infection first so files are not re-encrypted before you attempt to decrypt any .gdcb files.
Windows File History / System Restore
Indbygget Recover clean copies of affected files from a backup or restore point created before the infection instead of decrypting the .gdcb files. Tekniske detaljer
dyb specifikation| Encoding | Original file contents encrypted with AES-256 (Cipher Block Chaining) in GandCrab v1; the per-file/per-machine AES key is wrapped with an embedded RSA-2048 public key held by the attackers. |
| Byte order | Not applicable (encrypted ciphertext) |
| Container | The original file is overwritten/replaced with ciphertext and renamed with a trailing .GDCB extension (e.g. photo.jpg becomes photo.jpg.GDCB). |
| Encryption | AES-256 (CBC) for file data plus RSA-2048 to protect the AES key; later GandCrab versions (v4, v5) switched file encryption to Salsa20. |
| Typical size | Roughly the same as the original file plus a small amount of padding/metadata. |
| Structure | Renamed copy of the victim's file containing encrypted bytes; a plain-text ransom note named GDCB-DECRYPT.txt is dropped into every folder that has encrypted files. |
| Integrity | None exposed publicly |
| Platforms | Windows |
| Notes | GandCrab v1 was the first GandCrab release and the only one that used the .GDCB extension. It spread from late January 2018 through the RIG exploit kit via the Seamless malvertising campaign, and demanded payment in Dash cryptocurrency through a Tor payment site. Bitdefender, working with Europol and Romanian police, released a free decryptor for v1 in February 2018. |
| Ransom Note | GDCB-DECRYPT.txt |
| Malware Family | GandCrab (Ransom.GandCrab) |
| Udgivet | January 2018 |
GDCB-konverteringer
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