Office (OLE) / .XLSX malware analysis — malicious · 79225fb86abd84f1

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:45:23 Authoring application: Microsoft Excel

MD5: 4482c5cf2e69aeb87e928a35ce54022c SHA-1: 9785ab1df0ba8cec409f141fadb6a616477e864e SHA-256: 79225fb86abd84f1e6ebe90f33c877a3ce6ec9ac89d566fe8925548a6dc98d64

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 indicator of malicious intent. The presence of dangerous formula APIs like RUN=0 within the Auto_Open macro suggests the execution of arbitrary commands. While the exact commands are not fully discernible from the provided truncated script, the overall pattern points to a macro-based execution of potentially harmful code.

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` `14b1a61a6706199852f47f2eed69f48d54e3f433789611d1ca779f3771c39661`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6634 bytes

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