Office (OLE) / .XLSX malware analysis — malicious · c42f5a5dd598b693

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:34:07 Authoring application: Microsoft Excel

MD5: 1f168ac4f678476e493552e65995ae1a SHA-1: 592dc08e825b709ce6659b6fe0e0115f3b3c07c4 SHA-256: c42f5a5dd598b693fbe399ee2373e90ff0316935e923a81b39c4700fef60e0ea

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. The presence of dangerous formula APIs like RUN=0 indicates that the macro is designed to execute arbitrary commands. While the exact payload is not visible, the Auto_Open function strongly suggests an initial stage for downloading and executing a second-stage payload.

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` `c4ce9fa13fa31e659496b6307764067f4f75028c0da8824e900be611cf4c5017`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6544 bytes

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