Office (OLE) / .XLSX malware analysis — malicious · 631015aa09d5bcc9

MALICIOUS

Office (OLE) / .XLSX

138.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel First seen: 2022-07-13

MD5: 7012b13045922883b1f868dc45678a6d SHA-1: ac810d8d586593593a2e0cd4015e31187b646ee5 SHA-256: 631015aa09d5bcc94f36ab5a3cd50daea7a7a480c06fbdd4fb4cf1ffaff0c4ce

160 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1059.005 Visual Basic T1203 Exploitation for Client Execution

The sample is an Excel file containing Excel 4.0 macros, specifically an Auto_Open macro that is designed to execute automatically. The macro uses a dangerous function (RUN) and includes a lure to enable macros, indicating malicious intent. The macro attempts to download a second-stage payload from the URL http://nvelj12qyyfi03kqxy.xyz/i. and potentially save it as C:\zfbfg.ere.

Heuristics 4

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.
Macro/content-enable lure medium SE_ENABLE_LURE

Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_macros.txt` `3a08691eed72e5ed205a0b2d682f61d57bf1de10bae67e5c55da30ecdcba1b08`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	4335 bytes

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