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

Static analysis result for SHA-256 11f9782435cd6810…

MALICIOUS

Office (OLE) / .XLSX

329.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 1a1c3e03603ba50d851a93c9a4a48a3b SHA-1: ac05f61cfb2a389458eb7fa430499df4db9d5cb6 SHA-256: 11f9782435cd681089eaa70b8ccd4c7d9bb96a8c2aa2d17241849467581afb85
242 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The file contains Excel 4.0 macros, including an Auto_Open function that utilizes dangerous formula APIs like RUN. The macro attempts to construct a URL by concatenating strings and characters, which resolves to 'http://i.sfu.edu.ph/ds/161120.gif'. This suggests the macro's purpose is to download and execute a second-stage payload from this URL, aligning with the ClamAV detection of a downloader. The presence of the Auto_Open macro and the use of ShellExecute API point towards an initial access vector via spearphishing attachment.

Heuristics 6

  • 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.
  • ClamAV: Doc.Downloader.Docusign0521-9864805-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Docusign0521-9864805-0
  • Reference to ShellExecute API high SC_STR_SHELLEXEC
    Reference to ShellExecute API
  • 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.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://i.sfu.edu.ph/ds/161120.gif�

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
e17e7cc4a238aa7ef2e84a739a77bbc946bb2881b6aa82203097e9ab8210d20f		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6273 bytes

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