Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 19f8a394bb978006…

MALICIOUS

Office (OOXML)

155.8 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2021-06-28
MD5: 95b913ba51bfe34edbf7790ac67209ed SHA-1: c7260e3b594c5f5b3a089e3a3a16c26caa70e92f SHA-256: 19f8a394bb9780060ac23bfbc89facb257400da132900abc39b7290ae66bc12c
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 designed to download a payload from one of the two embedded URLs. The macros are reassembled from CHAR() and split formulas, indicating a deliberate attempt to obfuscate the payload delivery mechanism. The primary goal appears to be the execution of a second-stage payload hosted at the provided URLs.

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://engeferltda.com/vigI0sq9Z0/moon.html Referenced by macro
    • https://vishalzalafilms.com/rjoN5i2D/moon.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 114771 bytes
SHA-256: 8010a6501de1a7fb57904c8a165d3df40ad450d0e4c512e1b89dbd32b1fbc0e0
Preview script
First 1,000 lines of the extracted script
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... (truncated)