Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 6e09e57e017f6a0f…

MALICIOUS

Office (OOXML)

154.3 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2021-07-02
MD5: b8db7abae33e295b1782b7ce5266b8c4 SHA-1: 400455de84431a9c52965b77aa88a017c79625e0 SHA-256: 6e09e57e017f6a0fb646916211f4d5b06246aa6c744e7866a69458bbb206e387
182 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The file contains Excel 4.0 macros, which are reassembled from CHAR() and split formulas. These macros embed and reference two URLs, indicating an intent to download and execute a second-stage payload. The use of Excel 4.0 macros suggests a phishing attachment delivery method.

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.
  • 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.
  • 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://ssmdevelopers.in/4RaxIGAPtfPM/yu.html Referenced by macro
    • https://ramblerimport.com/hz4UhluT5au/yu.htmlReferenced 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/intlsheet1.bin 114422 bytes
SHA-256: 75671d724d6899f82f10be918456f4b8569f54253b0a4110770ac348ebb331f6
Preview script
First 1,000 lines of the extracted script
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... (truncated)