user@threatcheck.sh ~ threat-analysis
bash
$ analyze-threat Trojan:Win32/FormBook.NF!MTB
Trojan:Win32/FormBook.NF!MTB - Windows Defender threat signature analysis

Trojan:Win32/FormBook.NF!MTB - Windows Defender Threat Analysis

$ cat analysis.txt
=== THREAT ANALYSIS REPORT ===
Threat Name: Trojan:Win32/FormBook.NF!MTB
Classification:
Type:Trojan
Platform:Win32
Family:FormBook
Detection Type:Concrete
Known malware family with identified signatures
Variant:NF
Specific signature variant within the malware family
Suffix:!MTB
Detected via machine learning and behavioral analysis
Detection Method:Behavioral
Confidence:Very High
False-Positive Risk:Low

Concrete signature match: Trojan - Appears legitimate but performs malicious actions for 32-bit Windows platform, family FormBook

Summary:

This detection indicates a concrete identification of Trojan:Win32/FormBook.NF, a sophisticated information stealer known for keylogging, screenshot capture, and exfiltration of sensitive data. The threat utilizes various techniques including API hooking, process injection, abuse of legitimate system utilities (mshta, regsvr32, rundll32, PowerShell, BITS jobs), and scheduled tasks for persistence and malicious execution.

Severity:
High
VDM Static Detection:
Relevant strings associated with this threat:
 - FrmForca.resources (PEHSTR_EXT)
 - WindowsApp3.Resources.resources (PEHSTR_EXT)
 - AlgorithmSimulator.Properties.Resources (PEHSTR_EXT)
 - XigGSm.g.resources (PEHSTR_EXT)
 - !#HSTR:StringCodeForMshta.A!pli (PEHSTR_EXT)
 - !#HSTR:StringCodeForHooking.C!pli (PEHSTR_EXT)
 - !#HSTR:StringCodeForHooking.D!pli (PEHSTR_EXT)
 - !#HSTR:StringCodeForHooking.L!pli (PEHSTR_EXT)
 - !#HSTR:StringCodeForHooking.O!pli (PEHSTR_EXT)
 - !#HSTR:StringCodeForRegsvr32.A!pli (PEHSTR_EXT)
 - !#HSTR:StringCodeForRundll32.A!pli (PEHSTR_EXT)
 - rundll32 (PEHSTR_EXT)
 - !#HSTR:StringCodeForBITSJobs.A!pli (PEHSTR_EXT)
 - !#HSTR:StringCodeForPowerShell.G!pli (PEHSTR_EXT)
 - !#HSTR:StringCodeForScheduledTask.A!pli (PEHSTR_EXT)
 - !#HSTR:StringCodeForDataEncoding.D!pli (PEHSTR_EXT)
 - !#HSTR:StringCodeForHooking.J!pli (PEHSTR_EXT)
 - !#HSTR:StringCodeForHooking.K!pli (PEHSTR_EXT)
 - !#HSTR:StringCodeForRemoteFileCopy.B!pli (PEHSTR_EXT)
 - !#HSTR:ExecutionGuardrails (PEHSTR_EXT)
 - !#HSTR:StringCodeForFileDeletion.A!pli (PEHSTR_EXT)
 - !#HSTR:StringCodeForHooking.M!pli (PEHSTR_EXT)
 - !#HSTR:StringCodeForNetshHelperDLL.A!pli (PEHSTR_EXT)
 - !#HSTR:StringCodeForRemoteServices.A!pli (PEHSTR_EXT)
YARA Rule:
rule Trojan_Win32_FormBook_NF_2147912072_0
{
    meta:
        author = "threatcheck.sh"
        detection_name = "Trojan:Win32/FormBook.NF!MTB"
        threat_id = "2147912072"
        type = "Trojan"
        platform = "Win32: Windows 32-bit platform"
        family = "FormBook"
        severity = "Critical"
        info = "MTB: Microsoft Threat Behavior"
        signature_type = "SIGNATURE_TYPE_PEHSTR_EXT"
        threshold = "6"
        strings_accuracy = "Low"
    strings:
        $x_3_1 = {8d 52 01 66 89 06 8a ?? 8d 76 02 84 c0 75 ef 5e}  //weight: 3, accuracy: Low
        $x_3_2 = {33 c0 38 01 74 0d 8d 49 00 80 7c 08 01 ?? 8d 40 01 75 f6 33 c9 66}  //weight: 3, accuracy: Low
    condition:
        (filesize < 20MB) and
        (all of ($x*))
}
Known malware which is associated with this threat:
Filename: file.exe
d091f4b8dc052ab99ae7b816a30d155b2cbc660b5550ee994a0be6ba682e4593
20/01/2026
→VirusTotal↓Download Sample
Filename: ac390d3e36cf4922ce11ffff5bca9b2f11f6863d094fddca27f7c237ceb05b39
ac390d3e36cf4922ce11ffff5bca9b2f11f6863d094fddca27f7c237ceb05b39
29/12/2025
→VirusTotal↓Download Sample
Filename: 20ba741b01e8499cff8956a8d710b7d27009f33479a6122761cb691b8e546ac2
20ba741b01e8499cff8956a8d710b7d27009f33479a6122761cb691b8e546ac2
29/12/2025
→VirusTotal↓Download Sample
Filename: xloader.exe
18f5cac951415dfc29a7c41a77cd8878674035561d0425dfbefd8939ea368f0d
19/12/2025
→VirusTotal↓Download Sample
Remediation Steps:
Immediately isolate the infected system to prevent further compromise or data exfiltration. Perform a full system scan with up-to-date antivirus and remove all detected malicious files. Subsequently, reset all user and system credentials associated with or accessed from the compromised host, and thoroughly investigate for any established persistence mechanisms or signs of data exfiltration.
=== END REPORT ===
$ reanalyze-threat
This analysis was last updated on 19/12/2025. Do you want to analyze it again?
$ ls available-commands/
→ cd /home
user@threatcheck.sh:~$ ▊