Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 f67a572f2021f9fe…

MALICIOUS

Office (OOXML)

11.8 KB Created: 2021-05-08 16:46:29 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2021-06-20
MD5: da13bf8306429b5c7f5ac62fa4b1655c SHA-1: 0b9fa1b195e23669443c9b20c5acc1f7c405fc6c SHA-256: f67a572f2021f9fe0bdff42e20ba8b4525c89735c9b013815c7c464c1deaea61
168 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The sample is an OOXML document containing a VBA macro with an Auto_open subroutine. This subroutine utilizes WScript.Shell to execute the legitimate Firefox executable. This is likely intended to deceive the user into thinking they are interacting with a legitimate application while the macro performs other malicious actions in the background, such as downloading and executing a second-stage payload.

Heuristics 5

  • VBA project inside OOXML medium 4 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
    Matched line in script
    Dim objShell
    Set objShell = CreateObject("Wscript.shell")
    objShell.Run ("""C:\Program Files\Mozilla Firefox\firefox.exe""")
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Dim objShell
    Set objShell = CreateObject("Wscript.shell")
    objShell.Run ("""C:\Program Files\Mozilla Firefox\firefox.exe""")
  • 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.
  • Auto_Open macro low OLE_VBA_AUTO
    Auto_Open macro
    Matched line in script
    Attribute VB_Name = "Module1"
Sub Auto_open()

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) 831 bytes
SHA-256: fd5e0276ef18d1a49c14bfbb8f292f8e00b6ae9a31b1973e25b486449ad71100
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "Module1"
Sub Auto_open()

Dim objShell
    Set objShell = CreateObject("Wscript.shell")
    objShell.Run ("""C:\Program Files\Mozilla Firefox\firefox.exe""")
    Set objShell = Nothing

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 10752 bytes
SHA-256: 9af60568d3f5a53500dcf604a3558f590be3b636bbe06dda3ef05a0e9d59beac

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