Office (OOXML) / .XLSX malware analysis — malicious · e3c24a0843c7e08e

MALICIOUS

Office (OOXML) / .XLSX

113.6 KB Created: 2021-03-05 04:08:28 UTC Authoring application: Microsoft Excel 16.0300

MD5: f2c4eda294d331e6154c6f67e3e2f8ee SHA-1: fccf2bdaaf36699cb50a86d8443dd7944a15545d SHA-256: e3c24a0843c7e08ea07d45f4baba5eafcf1c9565ae809ca9da4a1ee8eb9b8163

120 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros, as indicated by the OOXML_XLM_MACROSHEET heuristic. The ClamAV detection further confirms its malicious nature. The embedded macro sheet is heavily truncated, but the presence of Excel 4.0 macros strongly suggests an intent to download and execute a second-stage payload, a common technique for malware delivery.

Heuristics 2

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.
ClamAV: Doc.Downloader.Trojan-bf70f023603538ee-bf70f023603538ee-9950269-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Doc.Downloader.Trojan-bf70f023603538ee-bf70f023603538ee-9950269-0

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `d2e0fc55c326c9b2dcf12dd036529ed2a587e28f7d0a6f1fc2c28097d582afea`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	10168 bytes

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