Office (OLE) / .XLSX malware analysis — malicious · b23df234eb9ca2b1

MALICIOUS

Office (OLE) / .XLSX

104.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel

MD5: 3d662482f2596988de3c94122187cddf SHA-1: 7fc7b7b755f0b231ad2b528a4312c15e6accd83d SHA-256: b23df234eb9ca2b1751ae74a032dfe7c684979b1ee3de230bb7da111be894c0e

120 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic for Applications T1204.002 Malicious File

The sample is an Excel file containing Excel 4.0 macros, specifically an Auto_Open macro, which is a strong indicator of malicious intent. The document body impersonates DocuSign to trick the user into enabling macros. The extracted URLs and the presence of 'rundll32.exe' and 'DllRegisterServer' in the document body suggest the macro is designed to download and execute a second-stage payload. The macro also attempts to reconstruct a URL from concatenated strings, which is a common obfuscation technique.

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.
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
Document signing service impersonation lure medium SE_DOCUSIGN_LURE

Document impersonates DocuSign, Adobe Sign, or a similar signing service in a signing-request context

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_macros.txt` `f6f94d67da6884829caad9c6254d35920c4ca40818ef183c6a43675671038d32`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	3048 bytes

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