Office (OLE) / .XLSX malware analysis — malicious · 7b2dceb8e365e5a8

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:41:45 Authoring application: Microsoft Excel

MD5: 387fb4560cba3805507d23461676c111 SHA-1: 8f0d7a0954e5f3987883638419a3a17baa3b199d SHA-256: 7b2dceb8e365e5a819eb7d4277f8321a94325e1c3de606436a1ca611abca520a

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a known technique for executing malicious code upon opening the workbook. The presence of dangerous formula APIs like RUN indicates the macro is designed to execute external commands or payloads. While no specific URLs or hashes were extracted, the Auto_Open macro strongly suggests a downloader or initial execution stage for further malicious activity.

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` `3b2bd07eea6b66a8dd4f7a795c92e9772ef1c6e57bea9f68f2ffb84924ac16bb`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6654 bytes

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