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

Static analysis result for SHA-256 018db555469f781a…

MALICIOUS

Office (OOXML) / .XLSX

233.7 KB Created: 2021-03-05 04:08:28 UTC Authoring application: Microsoft Excel 16.0300
MD5: 602db1a9f9d972c41d64ddb970968777 SHA-1: 6938f6db22096599a7cff9f1c87781a94f246e85 SHA-256: 018db555469f781ac6a7e812e9f6de51a3b8e8476ec42f0e9e8717b78259a427
182 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1105 Ingress Tool Transfer

The file contains Excel 4.0 macros that are reassembled from CHAR() and split formulas. These macros execute commands to create a directory at C:\ProgramData\flotsh and then download a DLL file named h4gf.dll from the URL http://195.123.222.194/campo/h/hC. This indicates a downloader functionality, aiming to retrieve and execute a second-stage payload.

Heuristics 4

  • Excel 4.0 macro sheet (1 sheet(s)) critical OOXML_XLM_MACROSHEET
    Spreadsheet contains an Excel 4.0 (XLM) macro sheet — XLM was a major Office malware vector during 2020-2022 and evaded many VBA-focused controls before Microsoft tightened XLM defaults. Even legitimate XLM use is rare in modern workbooks. The macro sheet is stored as XLSB/BIFF12 binary content, which many XML-only OOXML scanners miss.
  • XLM payload reassembled from CHAR()/split formulas critical OOXML_XLM_REASSEMBLED_PAYLOAD
    An Excel 4.0 macro sheet builds its payload inside the formula token stream by concatenating per-character CHAR() calls and string fragments, so no WinAPI name, shell command, or URL is ever contiguous in the .bin for a literal-bytes scan to find. Reassembling the formulas recovered download/execute API names, LOLBin commands (regsvr32/rundll32/mshta/wmic/powershell), or a payload URL — the de-obfuscated download-and-run kill chain.
  • ClamAV: Doc.Downloader.Trojan-bf70f023603538ee-bf70f023603538ee-9950269-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Trojan-bf70f023603538ee-bf70f023603538ee-9950269-0
  • 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://195.123.222.194/campo/h/hC

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.bin
efe19263199f13687f7cc92ee86bd0161479f83dae0dfc9a37f5cba0e3234552		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 11364 bytes

Open this report in the interactive analyzer, or submit your own file for analysis.