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

Static analysis result for SHA-256 cb7db7e2642eb0c0…

MALICIOUS

Office (OLE) / .XLS

179.2 KB Authoring application: Microsoft Excel
MD5: 04cc51f4e9439cf15ebad773dd87b59f SHA-1: 492da435dff63d373d0937bcc5f5e4c096f44cc8 SHA-256: cb7db7e2642eb0c0363caf63101e530db1e33ee2781df60f881b0f43ba4e188d
228 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer

The sample is an Excel file identified as malicious. It contains an embedded PE executable, indicated by the OLE_EMBEDDED_EXE heuristic. The presence of VBA macros, though not executable statements, suggests a potential delivery mechanism. The heuristics SC_STR_VIRTUALALLOC, SC_STR_LOADLIBRARY, and SC_STR_GETPROCADDRESS, along with SC_XOR_ENCODED, point towards the embedded executable's likely functionality of loading and executing code, possibly after decryption. The primary IOC is the embedded executable file itself.

Heuristics 6

  • XOR-encoded strings (key 0xDE) critical SC_XOR_ENCODED
    Found 5 Windows library/API name(s) XOR-encoded with single-byte key 0xDE: 'GetProcAddress', 'CreateProcessA', 'ExitProcess', 'CreateFileA', 'CreateFileW'
  • Embedded PE executable critical OLE_EMBEDDED_EXE
    MZ/PE header found inside document — possible embedded executable
  • Reference to LoadLibrary API high SC_STR_LOADLIBRARY
    Reference to LoadLibrary API
  • Reference to GetProcAddress API high SC_STR_GETPROCADDRESS
    Reference to GetProcAddress API
  • Reference to VirtualAlloc API medium SC_STR_VIRTUALALLOC
    Reference to VirtualAlloc API
  • VBA project contains no executable statements low OLE_VBA_MACROS
    Document contains a VBA project, but extracted modules only contain attributes/options/comments and no executable statements.

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
481031c20227961d1e7d207d0bb17c79a9001efbdb37ac509a4ff93acb047bf0		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 606 bytes
embedded_office_00010ceb.exe
0c5cdbf6f043780dc5fff4b7a977a1874457cc125b4d1da70808bfa720022477		 embedded-pe Office MZ+PE at offset 0x10CEB 114688 bytes

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