Office (OLE) / .XLSX malware analysis — malicious · 7bf67023a3399525

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:44:37 Authoring application: Microsoft Excel

MD5: cb6d388c5925b0199bcdaff7c913ae5b SHA-1: 51396536ec92f97d56c8e46f8bd95eeb96fd5f3e SHA-256: 7bf67023a339952571dc557c52e4105e4798b624fd1f6beff7066e4a6b35df0a

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

This Excel file contains Excel 4.0 macros, specifically an Auto_Open function, which is a known technique for executing malicious code upon opening the document. The presence of dangerous formula APIs in the Auto_Open macro indicates an intent to run arbitrary commands. The macro likely serves to download and execute a second-stage payload, although the specific payload and its destination are not detailed in the provided evidence.

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` `4a684c1068a77d36cac82e5d8e94f9fa6b2ca6a19e6c5bb6be6faf14fac6a7ff`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6707 bytes

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