Office (OLE) / .XLS malware analysis — malicious · 1f84394df24e1b59

MALICIOUS

Office (OLE) / .XLS

36.5 KB Created: 2020-11-27 11:45:57 Authoring application: Microsoft Excel First seen: 2022-02-19

MD5: 5a384b152871690cf7967822cc405e55 SHA-1: 3c9813663f572d55f877ab9a89ce374d31e11f64 SHA-256: 1f84394df24e1b599816da3c9af111b368dafa899c3849e03608cbefa57e3a35

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic for Applications T1059.001 PowerShell

The sample is an Excel 4.0 (XLM) macro-enabled spreadsheet. Critical heuristics indicate the presence of an Auto_Open defined name, which is a common technique for executing malicious code when the workbook is opened. The macro sheet contains a call to the RUN function, which is a dangerous API used to execute arbitrary code. This suggests the file is designed to download and 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` `e034fcf076e8d5d6907ac8766d6d2eec97ea5342505d1803539f7dce9f62854b`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6893 bytes

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