FormBook | Threat Level: high | Type: Infostealer

Cryptographic Identifiers

SHA256a99bac1e728dc56860037cee42d2b3f22c50f987e10e010db92f29f88b6f8521
MD5a5001f76ddb878e95ee9911c17b64ca2
File Typeexe
Size279.0 KB
First Seen2026-06-08
File Namea99bac1e728dc56860037cee42d2b3f22c50f987e10e010db92f29f88b6f8521
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: a99bac1e728dc56860037cee42d2b3f22c50f987e10e010db92f29f88b6f8521
  • MD5: a5001f76ddb878e95ee9911c17b64ca2

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: a99bac1e728dc568"
        threat_level = "high"
        first_seen = "2026-06-08"
    condition:
        hash.sha256(0, filesize) == "a99bac1e728dc56860037cee42d2b3f22c50f987e10e010db92f29f88b6f8521"
}

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 a99bac1e728dc56860037cee42d2b3f22c50f987e10e010db92f29f88b6f8521 # MD5 a5001f76ddb878e95ee9911c17b64ca2
TypeValueNote
sha256 a99bac1e728dc56860037cee42d2b3f22c50f987e10e010db92f29f88b6f8521 Sample:FormBook
md5 a5001f76ddb878e95ee9911c17b64ca2 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