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

Static analysis result for SHA-256 9cd35fa0778c9414…

MALICIOUS

Office (OLE) / .XLS

154.5 KB Created: 2021-10-27 10:31:49 Authoring application: Microsoft Excel
MD5: 72f8d29e91bf7ad2bdbc95d9783c0d5d SHA-1: fcef4f3fe498a30a954366861ec538fad9a3a52d SHA-256: 9cd35fa0778c941469378a96267de2933089868036a78e1d8c062dc9fc3625a5
202 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros, specifically an Auto_Open macro, which is a critical indicator of malicious intent. The macros reconstruct a URL, 'http://149.129.254.152:8080/6tfcnfucknugget4gpenis3dade5z6cpc', and also attempt to write to a file path 'C:\ProgramData\Fbg\SVKYBiV\VTg\x.rtf'. This suggests the macro is designed to download and execute a second-stage payload from the specified URL.

Heuristics 5

  • 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 (4 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.
  • 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://149.129.254.152:8080/6tfcnfucknugget4gpenis3dade5z6cpc
    • https://cdn.discordapp.com/attachments/911246617275957290/915526468073848872/xTpcaEZvwmHqwhoreniggagay.bin
    • https://cdn.discordapp.com/attachments/911246617275957290/915526473467719720/KsXtuXmxoZvgudVwhoreniggagay.bin
    • https://cdn.discordapp.com/attachments/911246617275957290/915526461379727370/GYRxsMXKtvwSwhoreniggagay.bin

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
2764e74cd038291d9796399c7d060c2b9d3173945c30a650a51612b0b1308976		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 2299 bytes

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