FormBook | Threat Level: high | Type: Infostealer

Cryptographic Identifiers

SHA25655d0817a4d8c4eb9def4eb0f0ac8d1ce0bac5ef2a6cec3ab9038339b28528605
MD500c4b77d1ef7b12fed63b4b525230109
File Typezip
Size683.2 KB
First Seen2026-05-20
File Name2025.11-(5)-PO-250301.zip
TagsFormBook, zip

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: 55d0817a4d8c4eb9def4eb0f0ac8d1ce0bac5ef2a6cec3ab9038339b28528605
  • MD5: 00c4b77d1ef7b12fed63b4b525230109

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: 55d0817a4d8c4eb9"
        threat_level = "high"
        first_seen = "2026-05-20"
    condition:
        hash.sha256(0, filesize) == "55d0817a4d8c4eb9def4eb0f0ac8d1ce0bac5ef2a6cec3ab9038339b28528605"
}

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 55d0817a4d8c4eb9def4eb0f0ac8d1ce0bac5ef2a6cec3ab9038339b28528605 # MD5 00c4b77d1ef7b12fed63b4b525230109
TypeValueNote
sha256 55d0817a4d8c4eb9def4eb0f0ac8d1ce0bac5ef2a6cec3ab9038339b28528605 Sample:FormBook
md5 00c4b77d1ef7b12fed63b4b525230109 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