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

Static analysis result for SHA-256 48202389d4eb5f83…

MALICIOUS

Office (OLE) / .XLSX

207.5 KB Created: 2021-10-27 10:31:49 Authoring application: Microsoft Excel
MD5: b6d5d1129bdc1379d5a50404b506ad6c SHA-1: ce0bf0eb18dc5cb4dc5ad49fb7dc5c0aa484f6a7 SHA-256: 48202389d4eb5f83420768a18baa114c9287a3a19d72648686db3bbcd0b1022b
202 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The sample contains Excel 4.0 macros, specifically an Auto_Open macro, which is a critical finding. The macros are designed to execute a command that reconstructs to 'mic process call call create "mshta C:\ProgramData\ZlCUOii zvpj.rtf"'. This command likely uses mshta to download and execute a payload from the reconstructed URL http://157.230.250.107:8080/mfkrmotherfuckeru6y82sasswhorehf9e, which is also identified as an IOC. The presence of the Auto_Open macro and the execution of a command to download and run a payload strongly indicate a malicious intent.

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://157.230.250.107:8080/mfkrmotherfuckeru6y82sasswhorehf9e
    • https://cdn.discordapp.com/attachments/911246617275957290/915526802779291658/dFUOuTxFQrXAwhoreniggagay.bin
    • https://cdn.discordapp.com/attachments/911246617275957290/915526808970084353/RbrKCqqjDPUwhoreniggagay.bin
    • https://cdn.discordapp.com/attachments/911246617275957290/915526814867263538/RqgAGRvHNwhoreniggagay.bin

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
b80f505d188f8445fafac89bab2c6a1f646fe6619cc3f4c7c65898fc88bda020		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 1969 bytes

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