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

Static analysis result for SHA-256 168f075ca37cbfae…

MALICIOUS

Office (OLE) / .XLS

332.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: ca14306a247cd7eb3921d1a45d85c40a SHA-1: 2399f4dff51510064548b32fb26b66b055421c23 SHA-256: 168f075ca37cbfaea76335bff20a1f8f1d0bee67c362fcdcd516b86050185174
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, specifically an Auto_Open macro, which is a critical indicator of malicious intent. The macros utilize the RUN function and CALL to execute a sequence of commands, including a reference to the ShellExecute API. The script also constructs a URL, 'https://birdexim.com/ds/231120.gif', which is likely used to download and execute a second-stage payload. The presence of the 'DocuSig' sheet name and the ClamAV detection 'Doc.Downloader.Docusign0521-9864805-0' further support this assessment.

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 https://birdexim.com/ds/231120.gif

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
33b6a73d5f0d6eaa82513d86953f6aef905a69517ef33e4eba1db75f4a178a6f		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6298 bytes

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