Office (OLE) / .XLSX malware analysis — malicious · fd9da1dd302c3f4d

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:37:40 Authoring application: Microsoft Excel

MD5: 229dc7e3dfe9635ce41e7fab0a966ba9 SHA-1: 3cf9510b5e7bd933708dec33ec5f1571ef762038 SHA-256: fd9da1dd302c3f4de38c5e15f54967bc35e2772877f9635b6c348fa40eb394f8

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell

The file contains Excel 4.0 (XLM) macro sheets, specifically triggering critical heuristics for an Auto_Open defined name and the use of dangerous formula APIs like RUN. The Auto_Open macro is designed to execute arbitrary commands upon opening the workbook, indicating a malicious intent to compromise the user's system. The presence of the RUN function within the XLM macro is a strong indicator of a downloader or executioner.

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` `10e636dcbc9105b796f3bc1c46b6b1d957f1ad2d9e5602571e4cc7afefc11739`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6882 bytes

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