Office (OLE) / .XLSX malware analysis — malicious · a72d5ba56f474bc4

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:45:46 Authoring application: Microsoft Excel

MD5: 84f7e6bf2376d7d18fdb9235913ac660 SHA-1: e8478fa8773e27db21ac3113d3f8732bbff1e220 SHA-256: a72d5ba56f474bc4a4ffd484fd248995374dfec1ae22db18ba446d5e869794f8

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1566.001 Spearphishing Attachment

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_AUTOOPEN_DEFINEDNAME indicate the presence of an Excel 4.0 Auto_Open macro. The OLE_XLM_DANGEROUS_FN heuristic specifically flags the use of the RUN function within the macro, which is commonly used to execute arbitrary commands. This suggests the macro is designed to download and execute a second-stage payload. No specific family could be identified.

Heuristics 3

Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME

oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN

Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN

Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_macros.txt` `6d33a6b5900242a66cb45eb761903505f9a93388bd823dbbec6f8fa34a898c9b`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6425 bytes

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