Office (OLE) / .XLSX malware analysis — malicious · 0a81bf98debfb24c

MALICIOUS

Office (OLE) / .XLSX

62.3 KB Created: 2021-12-16 23:53:43 Authoring application: Microsoft Excel

MD5: 70faaeac6a1df38bf289097106685c46 SHA-1: a7bc3db5b72b21b03269df8f01e8ef9088a778b4 SHA-256: 0a81bf98debfb24c784cfdfc1ff0e4e732b50fbf873cbee089dacf66bc14ce16

100 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros, indicated by the OLE_XLM_AUTOOPEN and OLE_XLM_AUTOOPEN_DEFINEDNAME heuristics. The document body displays a common lure to enable editing and content, which is also flagged by the SE_ENABLE_LURE heuristic. The extracted XLM macro contains a string that, when reconstructed, reveals a command to download a second-stage payload from 'http://87.251.86.178/pp/cc.html'. This macro execution is the primary malicious action observed.

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.
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` `1b5d2c0fd960b0ccb52c9814b8358c9c313741806cb2c5ef8340a3322e5a67a4`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	1391 bytes

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