FormBook | Threat Level: high | Type: Infostealer

Cryptographic Identifiers

SHA256e555bf7621da5d656e561964b7c51b2bdcdb8351856d9e30e91bc89088da7650
MD59d19cd8308c3fd59857b39d71105ad93
File Typezip
Size1026.5 KB
First Seen2026-05-21
File NameOSLA24090177_&_OSLA24090178pdf.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: e555bf7621da5d656e561964b7c51b2bdcdb8351856d9e30e91bc89088da7650
  • MD5: 9d19cd8308c3fd59857b39d71105ad93

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: e555bf7621da5d65"
        threat_level = "high"
        first_seen = "2026-05-21"
    condition:
        hash.sha256(0, filesize) == "e555bf7621da5d656e561964b7c51b2bdcdb8351856d9e30e91bc89088da7650"
}

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 e555bf7621da5d656e561964b7c51b2bdcdb8351856d9e30e91bc89088da7650 # MD5 9d19cd8308c3fd59857b39d71105ad93
TypeValueNote
sha256 e555bf7621da5d656e561964b7c51b2bdcdb8351856d9e30e91bc89088da7650 Sample:FormBook
md5 9d19cd8308c3fd59857b39d71105ad93 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