Office (OLE) / .XLSX malware analysis — malicious · 77f6c2ceea617098

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-25 10:38:53 Authoring application: Microsoft Excel

MD5: 8594cf358932c68c444c599d6d0ae261 SHA-1: 65a22b12deff96ed1268147f377e6521bb7b0751 SHA-256: 77f6c2ceea6170983b18e7774b9bb710ec86a5c6e817cbe995c8012a79dd43a0

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 finding. The presence of the 'RUN' function within these macros indicates the capability to execute arbitrary commands. This suggests the macro is designed to download and execute a second-stage payload. The document body contains heavily obfuscated text, further supporting a malicious intent.

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` `5a9bb48b60493b344625f58ef40e544fe1614c62d551308a295283599714078f`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6435 bytes

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