Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 856ef242bb1516d1…

MALICIOUS

Office (OOXML)

701.5 KB Created: 2020-05-11 14:19:29 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2020-12-25
MD5: 6fb3566edfb1275d0ec337fbbcad90b3 SHA-1: 51fcc79763cfa9f5b5474d5bf43ae994605c1795 SHA-256: 856ef242bb1516d1d83cc537f27b5444dc721b0064709b506ecb49256739a346
182 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros that leverage WinAPI functions such as URLDownloadToFileA and ShellExecuteA. These macros are designed to download a payload from the URL http://soloha.ua/ds/1.gif and execute it. This indicates 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://soloha.ua/ds/1.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: 7d03d2932e9d0328305d3d44be961a0334788a1cea908ac858a4459ecb289a6e
Preview script
First 1,000 lines of the extracted script
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