Malicious Office (OOXML) / .XLSX — malware analysis report

Static analysis result for SHA-256 7c9eb9658a178270…

MALICIOUS

Office (OOXML) / .XLSX

284.1 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2020-11-05
MD5: db2542266edb9fd50133f3e42e1574f3 SHA-1: d1a16bb26400b88770504f120d141ca2325ae38d SHA-256: 7c9eb9658a1782702301ed2c943c9f59f45c0ac2ffb7fb3e0da8ed6036f752a2
204 Risk Score

Malware Insights

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

The file contains critical heuristics indicating the presence of Excel 4.0 macros, which are known to be used for malicious purposes. These macros are designed to reconstruct and download a payload from the URLs http://oreillyautolawsuit.com/.png and http://oreillyautolawsuit.com/x.png. The primary URL http://oreillyautolawsuit.com/ is also present.

Heuristics 6

  • Excel 4.0 macro sheet (1 sheet(s)) critical 3 related findings OOXML_XLM_MACROSHEET
    Spreadsheet contains an Excel 4.0 (XLM) macro sheet — XLM was a major Office malware vector during 2020-2022 and evaded many VBA-focused controls before Microsoft tightened XLM defaults. Even legitimate XLM use is rare in modern workbooks. The macro sheet is stored as XLSB/BIFF12 binary content, which many XML-only OOXML scanners miss.
  • XLM payload reassembled from CHAR()/split formulas critical OOXML_XLM_REASSEMBLED_PAYLOAD
    An Excel 4.0 macro sheet builds its payload inside the formula token stream by concatenating per-character CHAR() calls and string fragments, so no WinAPI name, shell command, or URL is ever contiguous in the .bin for a literal-bytes scan to find. Reassembling the formulas recovered download/execute API names, LOLBin commands (regsvr32/rundll32/mshta/wmic/powershell), or a payload URL — the de-obfuscated download-and-run kill chain.
  • URL reconstructed from XLM cell array (2 URLs) critical OOXML_XLM_CELL_ARRAY_URL
    Excel 4.0 macro sheet stages its payload URL across individual numeric cells (one ASCII charcode per cell), inside an embedded HTA that uses VBScript Chr()/&-concat obfuscation, or split across multi-char fragment cells a download formula concatenates by reference (=A1&A2&… / CONCATENATE(...)). The reconstructed URL is invisible to literal-bytes URL extraction because it is never contiguous in the workbook stream. URLs were recovered by walking the BIFF12 record stream of every worksheet and macrosheet part and decoding RK/inline-string/shared-string cells in row-major and column-major order plus FORMULA cell-reference concatenation in token order.
  • XLM payload URL string (1 URL) info OOXML_XLM_PAYLOAD_URL
    An Excel 4.0 (XLM) macro-sheet workbook with download/execute evidence carries a literal http(s) URL stored as a (often UTF-16) string in the shared-string table or a cell. This is the next-stage payload host referenced by the macro download chain (URLDownloadToFile/ShellExecute); surfaced as an IOC.
  • VBA project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present
  • 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 http://oreillyautolawsuit.com/.png Referenced by macro
    • http://oreillyautolawsuit.com/x.pngReferenced by macro
    • http://oreillyautolawsuit.com/Referenced by macro

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 2647 bytes
SHA-256: 27d6200292cfa4324c165769041789fa2de3e9c8b2cf3850d43edc4635eed85b
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ЭтаКнига"
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 = "Лист1"
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 = "Class2"
Attribute VB_Base = "0{FCFB3D2A-A0FA-1068-A738-08002B3371B5}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = False
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False

Attribute VB_Name = "Class3"
Attribute VB_Base = "0{FCFB3D2A-A0FA-1068-A738-08002B3371B5}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = False
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False

Attribute VB_Name = "UserForm1"
Attribute VB_Base = "0{64C6955D-9C61-4398-82E1-615151C87BEA}{BA64BB06-7E31-46F7-9A88-05625F0FE2D1}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False

Attribute VB_Name = "UserForm2"
Attribute VB_Base = "0{5CA5A41A-7F88-461B-B647-470E533337D6}{3A2B599E-602F-49A4-863E-039647972FA9}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False

Attribute VB_Name = "UserForm3"
Attribute VB_Base = "0{4905251E-BAE5-4821-AB5A-12A20AA2A469}{2448AF6B-03DB-4175-AAEE-5559E033A0AC}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False

Attribute VB_Name = "Module1"

Attribute VB_Name = "Module2"

Attribute VB_Name = "Module3"

Attribute VB_Name = "Class1"
Attribute VB_Base = "0{FCFB3D2A-A0FA-1068-A738-08002B3371B5}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = False
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 25600 bytes
SHA-256: eaabbd5a8f61cd4842c49a014d04def9f9e0fc644ebab107a907c5ee8a51bb3e
xlm_sheet_00.bin xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 3990 bytes
SHA-256: 5e502e6fe72e1e9635f9b730623f8c2836864b36af0c9bed90fb3912ffb0f5a2
Preview script
First 1,000 lines of the extracted script
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