Office (OLE) / .XLSX malware analysis — malicious · 2c0c0973d7ff819b

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:28:36 Authoring application: Microsoft Excel

MD5: fe7853a3ae7d8c3b2c6611fd2cf59404 SHA-1: 5660d77ac6f3f0da92854f069db153a51c07438b SHA-256: 2c0c0973d7ff819b6a2a9109dbc3899981e952824ac4040b9afb2a04c2be6e87

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 (XLM) macro sheets with an Auto_Open defined name, indicating automatic execution upon opening. Critical heuristics identified the use of dangerous formula APIs, specifically the RUN function, which is commonly used to execute arbitrary commands. The presence of the RUN function within the Auto_Open macro suggests the primary intent is 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` `c663cf836dc4abb9769104b27c1ed0ff23cbcbde746e4ed9fdae227113506643`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6461 bytes

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