Office (OOXML) / .XLSX malware analysis — malicious · d4938e87e24325f0

MALICIOUS

Office (OOXML) / .XLSX

115.9 KB Created: 2021-03-16 13:14:06 UTC Authoring application: Microsoft Excel 16.0300

MD5: c437612b67444946d177354dad19b991 SHA-1: 91b56e73302463502b63ab5a857b68dc17fbef6b SHA-256: d4938e87e24325f05fd34ef10bc43a102fdd603354ea67c0d10da56460501d37

120 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic for Applications T1105 Ingress Tool Transfer

The sample is an Excel file containing Excel 4.0 macros. The macros are designed to download a file from the URL 'http://gropu.eup.xyz/camop/f/f' and save it as 'f.dll' in the system directory. This indicates a downloader functionality, aiming to retrieve and execute a second-stage payload. The ClamAV detection further confirms its malicious nature.

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` `192e84452a8e9c1cf7b8c66f557f19f853e336a416135de26c94e73baa5952df`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	3386 bytes

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