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

Static analysis result for SHA-256 a4e141090129f693…

MALICIOUS

Office (OLE) / .XLS

361.0 KB Created: 2021-12-17 13:23:39 Authoring application: Microsoft Excel@羀䶍Ǘ@澀듢Ǘ
MD5: 24bd46af8e27eb6862f683811dec700a SHA-1: 722969215c20db96ea461d3a0f92431d41327952 SHA-256: a4e141090129f69303721b0d7588db240464e1f547504501bce4bf5cb8641ea0
302 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1059.001 PowerShell T1218.004 Client Execution: Mshta T1059.003 Command and Scripting Interpreter: Windows Command Shell

The sample is an Excel 4.0 macro-enabled spreadsheet that uses an Auto_Open macro to execute a payload. The macro attempts to reconstruct a path to a file named 'FjEKVOTrGmfCpaEfPTy.rtf' in the ProgramData directory and then uses ShellExecute to run 'mshta.exe'. The document body explicitly prompts the user to enable content, indicating a social engineering lure. The reconstructed URL from the macro is 'C:\ProgramData\FjEKVOTrGmfCpaEfPTy.rtf', which is likely the path to the dropped payload.

Heuristics 8

  • 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 (3 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.
  • Reference to ShellExecute API high SC_STR_SHELLEXEC
    Reference to ShellExecute API
  • Reference to mshta.exe high SC_STR_MSHTA
    Reference to mshta.exe
  • 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.
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings
  • 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://cdn.discordapp.com/attachments/912724343694450701/923240963403579432/pISZyKjesusismyfriend.bin
    • https://cdn.discordapp.com/attachments/912722552516902995/923241569757315133/bYjgxeErgqxjesusismyfriend.bin
    • https://cdn.discordapp.com/attachments/912722552516902995/923241756005400627/UYHNGcmqCdGahtjesusismyfriend.bin

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
38c3128f3355b66d56d9de011d81f7a64b3b0376e7536f2516d091ca0d78faac		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 1908 bytes

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