Office (OOXML) / .XLSX malware analysis — malicious · 2775b71e3fbe5eb7

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 8b131127e123059501c8a2b97f83dcf0 SHA-1: f4347e353cf7a153dcc4c17ce71365b1174dedad SHA-256: 2775b71e3fbe5eb7c6edea36fc86496b5c41da6c6ed3442777e7438ba181a25b

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic firing indicates the presence of Excel 4.0 macros. The extracted macro content, though truncated, suggests an attempt to write to a file path that resembles a document, likely to stage a payload. This indicates a downloader functionality, aiming to fetch and execute further malicious content.

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` `23f1f696804cfaab6e76de9cd9dc8a758917b2cd62ee5802d7f1a2a7db3aeabb`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	117394 bytes

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