SquirrelWaffle — Office (OLE) malware analysis

Static analysis result for SHA-256 4405a176cbc81f0a…

MALICIOUS

Office (OLE)

247.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2021-11-02
MD5: d9e17aa50c1d8f9ebb3b5cfbf54ad9b5 SHA-1: 5f7b4cb20edb8c16a860cd072123971595f8050f SHA-256: 4405a176cbc81f0a2fdb111a3d5895a55376693bd24b0783f1dcc0d1f03bcaa2
262 Risk Score

Malware Insights

SquirrelWaffle · confidence 95%

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

The file contains Excel 4.0 macros, specifically an Auto_Open macro that utilizes dangerous functions. These macros reconstruct and reference three URLs, indicating an intent to download and execute a second-stage payload. ClamAV detection confirms this behavior, identifying the sample as a downloader.

Heuristics 6

  • ClamAV: Xls.Downloader.SquirrelWaffle1021-9903731-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.SquirrelWaffle1021-9903731-0
  • 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), across individual numeric cells (one ASCII charcode per cell), or split across multi-char fragment cells a download formula concatenates by reference (=A1&A2&… / CONCATENATE(...)). 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, LABELSST/RK/NUMBER cells, and FORMULA cell-reference concatenation in token order.
  • 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://samtnpy.org/bveCGKTX/ghb.html Referenced by macro
    • https://massngo.org/dXKvyKV9v8c/ghb.htmlReferenced by macro
    • https://vathiriyar.org/uy0Tk0keJUr/ghb.htmlReferenced by macro

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 11469 bytes
SHA-256: 8038cb32870f91f07ba8d77d2b38d0de4989e88a9f0271274f420bb3e000a522
Preview script
First 1,000 lines of the extracted script
' 0085     13 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  Shee
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Simbb
' 0085     17 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet (4
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Simbb
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Simbb
' 0085     11 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, hidden -  GG
' 0085     13 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, hidden -  Brer
' 0085     13 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, hidden -  Brer
' 0085     13 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, hidden -  Brer
' 0085     13 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, hidden -  Brer
' 0085     13 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, hidden -  Brer
' 0018     29 LABEL : Cell Value, String Constant - _xlfn.ARABIC hidden len=2 ptgErr  *INCOMPLETE FORMULA PARSING* Remaining, unparsed expression: b'\x1d'
' 0018     29 LABEL : Cell Value, String Constant - _xlfn.CONCAT hidden len=2 ptgErr  *INCOMPLETE FORMULA PARSING* Remaining, unparsed expression: b'\x1d'
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  Simbb!F1 
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell V
... (truncated)