Office (OLE) / .XLSX malware analysis — malicious · 9581ad1909909b7e

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:45:48 Authoring application: Microsoft Excel

MD5: f83499fe311cc8eeaa2c93309432de9f SHA-1: dbb08a7a95794536074837bc8040b50e77dcdf52 SHA-256: 9581ad1909909b7e6c7b72c9ab793a8e0214b405f4605862dc93c48efdb8268b

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The file contains Excel 4.0 (XLM) macro sheets, specifically triggering critical heuristics for an Auto_Open defined name and the use of dangerous formula APIs like RUN. This indicates the macro is designed to execute commands upon opening the spreadsheet. While the exact payload is not visible, the presence of the RUN function strongly suggests it's intended 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` `d276db66a03c38f78f485dd76ef37c6a22069eda7336a9d46b01b2e466ba0e91`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6867 bytes

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