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

Static analysis result for SHA-256 16b305f201f5707a…

MALICIOUS

Office (OLE) / .XLSX

145.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel
MD5: 5ebac616769496d22182cd39c2926766 SHA-1: c59ae34c992664d19b6825b66dc6b2536f9f67ad SHA-256: 16b305f201f5707a4ba8d91b305389af7f4fa9dbb8aa23bd8e41b359b43c2b0c
262 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The file contains Excel 4.0 macros, specifically an Auto_Open macro, which is a critical finding. These macros are designed to execute and download payloads from multiple URLs. The reconstructed document body reveals the concatenation of strings to form URLs and the command 'DllRegisterServer' along with a path 'SysWow64\Windows\', indicating a likely attempt to download and register a malicious component.

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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