Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 915a6dfd6acccfc7…

MALICIOUS

Office (OOXML)

357.7 KB Created: 2020-05-11 14:19:29 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2020-12-25
MD5: ff03cfb12f7c86fcfeb0b03cdeff8a7e SHA-1: 8f4f9c304508409864049d370a20568a018d261d SHA-256: 915a6dfd6acccfc7c099d5fdd6fdb452f3372b051f0f5a54f690da8bfbe7e8a1
182 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer T1204.002 Malicious File

This Excel file contains Excel 4.0 macros that leverage WinAPI functions like URLDownloadToFileA and ShellExecuteA. The macros are designed to download a file from the embedded URL http://brvgo.com/ds/161120.gif and execute it, indicating a downloader or droppper functionality.

Heuristics 4

  • Excel 4.0 macro sheet (1 sheet(s)) critical 2 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.
  • Binary XLM macro sheet with WinAPI/download strings critical OOXML_XLM_BINARY_WINAPI_STRINGS
    Excel 4.0 macro sheet is stored as BIFF12/XLSB binary data and contains Win32 download or process-execution API strings such as URLDownloadToFileA, ShellExecuteA, or CreateDirectoryA. These strings are high-signal in XLM macro sheets and catch payload-download macros that XML-formula scanners cannot parse.
  • URL reconstructed from XLM cell array (1 URL) 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.
  • 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://brvgo.com/ds/161120.gif Referenced by macro

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.bin xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 54253 bytes
SHA-256: b365bc31805c0196d6054bfcb687db4f0657375bd5ef192704b8f93493741977
Preview script
First 1,000 lines of the extracted script
�  �  �   @      ��������    �      �       �   �  �  �     r   D   @   d           � $        �                   �   �   �  �  %      ��    & �  ����        �  <         �         <         �         <         8,        <                   < �   �   q         < �   �   8
        �  �  %      ��    &                        �    &�           E       DG      �  Ao      � �       �   T I T J G T R U I T G R U I T G R U I R T G U I G T R U T G R U I T G R T G R I U G T R I U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U S G T R U R T U U T R U   J    � T I T J G T R U I T G R U I T G R U I R T G U I G T R U T G R U I T G R T G R I U G T R I U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U S G T R U R T U U T R U A�      l�          Y      t g r r g d y y r t g r y g t r y u    y U Y Y U Y R U Y U u y T Y y t T Y y Y E R A0     %      ��    &                        �    �         �   F E R T R J H T R J H T G R H J Y T Y T Y T T G R H J G T R H T R G H H T H J T J H G T R J H T R H J T G R H J T R H J T R G H J T G R H J T G R H J G T R H T R T H J H J T R T R H T R J T R G H J G T R H J G T R H J G T R J H T G R H J G T R J H G T R H J R T G H J G T R H G T R H T G R H T G R H T R T G T G R T R H J T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T H T G H H G T J G T J G T R H J T G R H J R T G H J R T G H J   �    � F E R T R J H T R J H T G R H J Y T Y T Y T T G R H J G T R H T R G H H T H J T J H G T R J H T R H J T G R H J T R H J T R G H J T G R H J T G R H J G T R H T R T H J H J T R T R H T R J T R G H J G T R H J G T R H J G T R J H T G R H J G T R J H G T R H J R T G H J G T R H G T R H T G R H T G R H T R T G T G R T R H J T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T H T G H H G T J G T J G T R H J T G R H J R T G H J R T G H J    R T A0     %      ��    &                        �    �         �   F E R Y T T Y T Y T R J H T R J H T G R H J T G R H J G T R H T R G H H T H J T J H G T R J H T R H J T G R H J T R H J T R G H J T G R H J T G R H J G T R H T R T H J H J T R T R H T R J T R G H J G T R H J G T R H J G T R J H T G R H J G T R J H G T R H J R T G H J G T R H G T R H T G R H T G R H T R T G T G R T R H J T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T H T G H H G T J G T J G T R H J T G R H J R T G H J R T Y T Y T Y T Y T T Y G H J   �    � F E R Y T T Y T Y T R J H T R J H T G R H J T G R H J G T R H T R G H H T H J T J H G T R J H T R H J T G R H J T R H J T R G H J T G R H J T G R H J G T R H T R T H J H J T R T R H T R J T R G H J G T R H J G T R H J G T R J H T G R H J G T R J H G T R H J R T G H J G T R H G T R H T G R H T G R H T R T G T G R T R H J T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T H T G H H G T J G T J G T R H J T G R H J R T G H J R T Y T Y T Y T Y T T Y G H J    R T A0      �         �   F E R T R J H T R J H T G R H J T G R H J G T R H T R G H H T H J T J H G T R J H T R H J T G R H J T R H J T R G H J T G R H J T G R H J G T R H T R T H J H J T R T R H T R J T R G H J G T R H J G T R H J G T R J H T G R H J G T R J H G T G F G R H J R T G H J G T R H G T R H T G R H T G R H T R T G T G R T R H J T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T H T G H H G T J G T J G T R H J T G R H J R T G H J R T G H J   �    � F E R T R J H T R J H T G R H J T G R H J G T R H T R G H H T H J T J H G T R J H T R H J T G R H J T R H J T R G H J T G R H J T G R H J G T R H T R T H J H J T R T R H T R J T R G H J G T R H J G T R H J G T R J H T G R H J G T R J H G T G F G R H J R T G H J G T R H G T R H T G R H T G R H T R T G T G R T R H J T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T H T G H H G T J G T J G T R
... (truncated)

Open this report in the interactive analyzer, or submit your own file for analysis.