Office (OOXML) / .XLSX malware analysis — malicious · 13b621c377bf201b

MALICIOUS

Office (OOXML) / .XLSX

70.3 KB Created: 2021-03-14 21:05:29 UTC Authoring application: Microsoft Excel 16.0300

MD5: cdb4ea173e760c17c878e8ef971ca44c SHA-1: cb2435438ee50aa5b7d8824fea05dfc551cefaa5 SHA-256: 13b621c377bf201be03f90e6b7d800b29ffa47419646ff2412e99eb8d22ad709

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File

The file is an Excel spreadsheet containing Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET heuristic. These macros are likely designed to download and execute a secondary payload, a common technique for initial access and further infection. The specific actions of the macros are not fully discernible due to truncation, but their presence strongly suggests malicious intent.

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` `6943b4eed72d182d7c88c9e4cefa85f51d82eeee1c3a052af14b3788761d2102`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	88880 bytes

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