FormBook | Threat Level: high | Type: Infostealer

Cryptographic Identifiers

SHA256a71a378d71f0720844e05051cee3116be3d32e9c9b6ef59d24f499fcbf6e8a2d
MD5a25e34db105c73cbc2f7499176cacd5a
File Typecab
Size775.6 KB
First Seen2026-05-20
File NamePayment_Advice_pdf.cab
Tagscab, 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: a71a378d71f0720844e05051cee3116be3d32e9c9b6ef59d24f499fcbf6e8a2d
  • MD5: a25e34db105c73cbc2f7499176cacd5a

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: a71a378d71f07208"
        threat_level = "high"
        first_seen = "2026-05-20"
    condition:
        hash.sha256(0, filesize) == "a71a378d71f0720844e05051cee3116be3d32e9c9b6ef59d24f499fcbf6e8a2d"
}

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 a71a378d71f0720844e05051cee3116be3d32e9c9b6ef59d24f499fcbf6e8a2d # MD5 a25e34db105c73cbc2f7499176cacd5a
TypeValueNote
sha256 a71a378d71f0720844e05051cee3116be3d32e9c9b6ef59d24f499fcbf6e8a2d Sample:FormBook
md5 a25e34db105c73cbc2f7499176cacd5a 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