Office (OLE) / .XLSX malware analysis — malicious · 3e884593614ce8bb

MALICIOUS

Office (OLE) / .XLSX

35.5 KB Created: 2020-11-25 10:36:17 Authoring application: Microsoft Excel

MD5: 96ed2b7cd3bc6f5db750088ca11f0953 SHA-1: 56c7b0dd2d2595853e9003ed194109c1a8944b1e SHA-256: 3e884593614ce8bbac7e330bca6a91a91d3944a1dfe39fb44eba4ad48b778386

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical heuristic firing. This indicates that the macro will execute automatically upon opening the workbook. The presence of dangerous formula APIs like RUN further suggests malicious intent, likely to download and execute a second-stage payload. No specific family could be identified, but the technique is common for initial execution.

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` `73e6cbfa8505db04575e4c9854c5786ae6c04b3d51f4b3de76d10f3013b58660`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6472 bytes

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