Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 a4419b80e191eed4…

MALICIOUS

Office (OOXML)

131.7 KB Created: 2021-09-04 13:16:06 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2021-09-22
MD5: 8e8e209c25f6cc22d0fbb46848e81c28 SHA-1: bc2c280493aa8f79c5e37df929ec45234abe1c80 SHA-256: a4419b80e191eed42ac8a95f9387d955d9532fbab97a8a740899c15a5f924006
160 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

This Excel document contains an Auto_Open VBA macro that executes a shell command. The macro attempts to run 'curl.exe' which is likely intended to download and execute a second-stage payload. The presence of the Auto_Open macro and the Shell() call strongly indicate malicious intent.

Heuristics 4

  • VBA project inside OOXML medium 3 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_Open macro
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 724 bytes
SHA-256: d5de35f9b4213f75a2d8de39e90f1521522bdb6ec7e7fb614585632f713061b4
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "Module1"
Sub Auto_Open()
    Dim Var As String
    Var = "curl.exe"
    Shell Var
End Sub

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
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 13312 bytes
SHA-256: a96b525dc1636ff8370c8f7b1fc1386a19a129fa7323fc7030ff198ad9513753

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