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

Static analysis result for SHA-256 05f6bd751c23bf57…

MALICIOUS

Office (OLE) / .XLSX

145.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel
MD5: 4f193cc799b2ee35fd23c45b2e1b694f SHA-1: e437bc300d12539e1947f3b79e675e79213e1404 SHA-256: 05f6bd751c23bf57aca5dcf5706eec329d215700b6fc009274d66a2fbfb21130
262 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The sample contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical indicator of malicious intent. These macros are designed to execute dangerous functions and reconstruct URLs from cell arrays. The reconstructed URLs, such as 'https://torostripinginc.com/old/V6BBS9ai/', are likely used to download and execute a second-stage payload, as indicated by the 'DllRegisterServer' string and the ClamAV detection 'Doc.Downloader.EmotetRed02222-9938635-0'.

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.
  • URL reconstructed from XLM cell array (5 URLs) critical OLE_XLM_CELL_ARRAY_URL
    Excel 4.0 macro sheet stages its payload URL across the BIFF8 Shared String Table (one quoted-char SST entry concatenated with & at runtime) or across individual numeric cells (one ASCII charcode per cell). The reconstructed URL is invisible to literal-bytes URL extraction because it is never contiguous in the workbook stream. URLs were recovered by walking the BIFF8 record stream and decoding SST entries plus LABELSST/RK/NUMBER cells.
  • ClamAV: Doc.Downloader.EmotetRed02222-9938635-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.EmotetRed02222-9938635-0
  • 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://torostripinginc.com/old/V6BBS9ai/
    • https://geologyadventures.com/error/vEsebODbHUw/
    • https://dev.woodiewin.com/wp-admin/Humbse55L82p72PIbbA/
    • https://xxden.online/wp-content/ge6YV52pidqe/
    • https://firebirdtaclub.com/_borders/TMFaFAVVxivebh/

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
1574ee13450fd34682012e2ebea7c020d326605272204fb688e7873d4a7c8165		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6756 bytes

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