Office (OLE) / .XLSX malware analysis — malicious · d6e3bc02b85bfda3

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:43:32 Authoring application: Microsoft Excel

MD5: 64dea04c0565b4294ba22c919ca8f437 SHA-1: d99f9fea432753c228b09ac659c222a4afc5f454 SHA-256: d6e3bc02b85bfda3b7a7d2f339f30d5df039257980bce1dd199d17a3709baa01

140 Risk Score

Malware Insights

MITRE ATT&CK

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

The file contains Excel 4.0 (XLM) macros, specifically an Auto_Open defined name, which is a critical indicator of malicious intent. The presence of the RUN function within the XLM macro indicates that the macro is designed to execute arbitrary commands upon opening. This is a common technique for initial payload delivery. While the specific payload is not detailed, the mechanism points to a macro-based downloader.

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` `e534a8da1dcc0e616b2920224b2b09f0445bd56f6a1e2b325e71a324c26eccfd`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6617 bytes

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