Office (OLE) / .XLSX malware analysis — malicious · c96b13b44f8ccb37

MALICIOUS

Office (OLE) / .XLSX

105.5 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel First seen: 2022-05-31

MD5: 10c63b3f4515c461424bd73439ed0489 SHA-1: 454af6286cf63be848f7c29cbc03eedda24d1ee8 SHA-256: c96b13b44f8ccb37a1d97604c24825e1d6c4e8f17e199c3428a534db2a5a53fd

120 Risk Score

Malware Insights

MITRE ATT&CK

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

The sample contains Excel 4.0 macros with an Auto_Open entry, indicating automatic execution upon opening. It also includes a lure to enable macros, impersonating DocuSign. The extracted URLs and the `rundll32.exe DllRegisterServer` command suggest the macro's purpose is to download and execute a second-stage payload from one of the listed URLs.

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` `1f3a9e9f425000bccc6ecbbba5371f1a3b0a17ea072b52992d451728caf3ab45`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	3742 bytes

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