Malicious Office (OLE) / .XLS — malware analysis report

Static analysis result for SHA-256 c91237bf50904ffb…

MALICIOUS

Office (OLE) / .XLS

61.5 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 0521905a4f012538c02de08a840c6cce SHA-1: 973a7b864f3b27abea600664263b535f3ca0182e SHA-256: c91237bf50904ffb92464148483a346d579b4378400e6c72dd32b27132942cbb
160 Risk Score

Malware Insights

MITRE ATT&CK
T1566.002 Spearphishing Attachment T1204.002 Malicious File T1059.001 PowerShell T1218.011 Rundll32

The sample is an Excel 4.0 macro-enabled spreadsheet that impersonates DocuSign to trick users into enabling macros. Upon enabling, it uses a 'rundll32' command to execute a DLL, likely a payload. The macro sheet contains an Auto_Open entry, indicating automatic execution. The presence of a lure to enable macros and the execution via rundll32 strongly suggest a downloader or initial access stage.

Heuristics 5

  • 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.
  • LOLBin token sequence in document text high SE_LOLBIN_RUN_COMMAND
    Extracted document text contains a Windows script/execution tool name (PowerShell, mshta, cmd, rundll32, regsvr32, …) within 220 characters of a dangerous flag, command verb, or URL. This is a visible 'run this' instruction in HTML/PDF/RTF lure bodies, or — in macro-laden Office files — the macro's own string-pool entries appearing adjacent in extracted text.
  • 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.

FilenameKindSourceSize
xlm_macros.txt
075072a41717adc301f689cf06a6c75f7ae4978d8de5ff68a306276ec79c0f60		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 2718 bytes

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