Office (OOXML) / .XLSX malware analysis — malicious · d193169de5e8894c

MALICIOUS

Office (OOXML) / .XLSX

53.6 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000

MD5: f2236bebbb2ed3026ba36e3903826ce6 SHA-1: 0181fb9bcdbff06faf2185f97fd8a2c99d6e7817 SHA-256: d193169de5e8894c719a420fa4e8f67864aa58b7ccba60d6e69e811313fb05f5

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic firing indicates the presence of Excel 4.0 macros within the XLSX file. Analysis of the macro content reveals attempts to download and execute a file named 'update.exe' from a location that appears to be constructed from concatenated strings, likely representing a malicious URL. This suggests the primary function of the macro is to act as a downloader for further malicious payloads.

Heuristics 1

Excel 4.0 macro sheet (1 sheet(s)) critical 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `b6110ceecb9fe6792e2c1b87c34c8eae9f78ae032b75af47e1eeb7c9a939664c`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	7269 bytes

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