Office (OLE) / .XLS malware analysis — malicious · 7a89a04ff27d6fe5

MALICIOUS

Office (OLE) / .XLS

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

MD5: 19b5bbd4478a50df5b886c7c9168ec59 SHA-1: 9c84634a5685ebe2f75b2b3eecffc7c2748bd621 SHA-256: 7a89a04ff27d6fe5e0d9249feee09c24989b074aa75e5563f755a7a279c62e5e

140 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment

The critical heuristics indicate the presence of Excel 4.0 macros with dangerous functions, specifically an Auto_Open entry. The extracted macro script reveals it constructs and executes a PowerShell command to download a file from 'https://bit.ly/3djeHvo' and save it as 'ts.exe' in the user's AppData directory, subsequently executing it. This indicates a macro-based downloader designed to execute 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` `e204756ed96eb44056e8fd6319c54ce98aa877b14f991823fe06f2b1ebfae936`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	1236 bytes

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