Office (OLE) / .XLS malware analysis — malicious · 40358c71d61842d9

MALICIOUS

Office (OLE) / .XLS

268.0 KB Created: 2021-02-06 22:23:31 Authoring application: Microsoft Excel

MD5: 2bad49b001757609246576caed4ba68d SHA-1: aebfce70c32d822e06afbd51ab5067fc8ac6b36e SHA-256: 40358c71d61842d92d209014c68fb5ba7e8c8c0380ba75893c6d7cca7e6749e4

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of Excel 4.0 macros designed to execute code. The extracted macro script confirms this by constructing and executing a PowerShell command. This command is designed to download a file from 'https://preview.tinyurl.com/ya7aust2', save it as 'sv.exe' in the user's AppData directory, and then execute it, indicating a downloader or dropper functionality.

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` `39994359948cb34fd5a8cd7143a848c9a9b261bf6040805b510ccdb8ca272bdb`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	1250 bytes

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