FormBook | Threat Level: high | Type: Infostealer

Cryptographic Identifiers

SHA2564de51fe054d8c489dc9b4f7f58e49f23a5cdb3dba8c5d68e92d4a0be3440a257
MD5f384b064e89c9b2e15ba21ea9f26e3c8
File Typeexe
Size1138.5 KB
First Seen2026-05-21
File NameGSTP_-_K3E0035.exe
Tagsexe, FormBook

Malware Family: FormBook

FormBook, MaaS stealer'dır.

TypeInfostealer
Programming LanguageC
Target PlatformWindows
C2 ProtocolHTTP
PurposeForm verisi hırsızlığı
First Seen Year2016
AliasesxLoader

Threat Indicators (IOC)

  • SHA256: 4de51fe054d8c489dc9b4f7f58e49f23a5cdb3dba8c5d68e92d4a0be3440a257
  • MD5: f384b064e89c9b2e15ba21ea9f26e3c8

You can verify all hash values of this sample on VirusTotal.

System Cleanup Guide

  1. Disconnect the system from the network immediately
  2. Yeni bir cihazdan banka hesabı, sosyal medya ve e-posta şifrelerini değiştirin
  3. Move crypto wallets to a new address and abandon the old ones
  4. Start a full scan with up-to-date antivirus
  5. Clear saved browser passwords and enable 2FA
  6. Sign out of all sessions on every affected service

YARA Rule Hints

rule FormBook_SHA256 {
    meta:
        description = "FormBook sample: 4de51fe054d8c489"
        threat_level = "high"
        first_seen = "2026-05-21"
    condition:
        hash.sha256(0, filesize) == "4de51fe054d8c489dc9b4f7f58e49f23a5cdb3dba8c5d68e92d4a0be3440a257"
}

FormBook — Malware Profile

FormBook web form verisi ve credential hırsızı. SmartAssembly paketleyici. İspanyolca LATAM elektrik faturası lür.

Malware Type
Infostealer
Programming Language
C
C2 Protocol
HTTP
Target Systems
Windows
Also Known As (AKA)
xLoader

Technical Details

C dili, Windows API hooking (form grabbing), HTTP POST C2, browser form stealer, keylogger, screenshot, clipboard monitor, process injection (process hollowing)

Attribution / Threat Actor

ABD'de gelistirilmis; satis darknet forumlari uzerinden yapilmis. Dunya genelindeki multuple suc gruplarina hizmet veren MaaS platformu.

Capabilities & Behavior

Tarayıcı Kimlik Bilgileri
Çerez Hırsızlığı
Kripto Cüzdan Çalma
Sistem Bilgisi
Ekran Görüntüsü
FTP/SSH İstemci Şifreleri
E-posta İstemcisi Çalma
Veri Sızıntısı

IOC List (2 indicators)

IOC — FormBook
# SHA256 4de51fe054d8c489dc9b4f7f58e49f23a5cdb3dba8c5d68e92d4a0be3440a257 # MD5 f384b064e89c9b2e15ba21ea9f26e3c8
TypeValueNote
sha256 4de51fe054d8c489dc9b4f7f58e49f23a5cdb3dba8c5d68e92d4a0be3440a257 Sample:FormBook
md5 f384b064e89c9b2e15ba21ea9f26e3c8 Sample:FormBook

C2 Servers (5 recorded servers for this family)

Address Type Port Protocol Status Country
45.61.136.16 ip 80 HTTP active US
hxxp://freeupgrades.net/s1xt/ domain 80 HTTP inactive US
103.75.160.239 ip 443 HTTPS inactive HK
3.29.19.86 ip — TCP inactive —
form-book.club domain 80 HTTP sinkholed —

C2 addresses are provided only from malware samples manually verified by the KEYDAL team. Commercial use is prohibited.

Tags
formbookinfostealermalwarehighsha256hash-analizi