Malicious RTF — malware analysis report

Static analysis result for SHA-256 dcb9d569e4ba3069…

MALICIOUS

RTF

107.9 KB First seen: 2019-05-16
MD5: 2873cda8710e955ce116597b1b303ad5 SHA-1: 250829881b198d0b8538bd62d0341914c560511e SHA-256: dcb9d569e4ba30699eabd7f47a07fd117dd74d89b78dca3fb44b2225a5f50ab2
220 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF document contains heuristics indicating the exploitation of CVE-2017-11882 through an embedded Equation Editor object. This vulnerability allows for arbitrary code execution when the document is opened. The presence of OLE object data and the specific Equation Editor ProgID strongly suggest this attack vector.

Heuristics 6

  • Split hex Equation Editor ProgID + OLE object critical CVE likely RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
  • Heap-spray pattern detected high SC_HEAP_SPRAY
    Repeated 0x0C bytes found
    Disassembly
    Attempted x86 opcode disassembly
    00000034  0c0c              or al, 0xc
00000036  0c0c              or al, 0xc
00000038  0c0c              or al, 0xc
0000003A  0c0c              or al, 0xc
0000003C  0c0c              or al, 0xc
0000003E  0c0c              or al, 0xc
00000040  0c0c              or al, 0xc
00000042  0c0c              or al, 0xc
00000044  0c0c              or al, 0xc
00000046  0c0c              or al, 0xc
00000048  0c0c              or al, 0xc
0000004A  0c0c              or al, 0xc
0000004C  0c0c              or al, 0xc
0000004E  0c0c              or al, 0xc
00000050  0c0c              or al, 0xc
00000052  0c0c              or al, 0xc
00000054  0c0c              or al, 0xc
00000056  0c0c              or al, 0xc
00000058  0c0c              or al, 0xc
0000005A  0c0c              or al, 0xc
0000005C  0c0c              or al, 0xc
0000005E  0c0c              or al, 0xc
00000060  0c0c              or al, 0xc
00000062  0c0c              or al, 0xc
00000064  0c0c              or al, 0xc
00000066  0c0c              or al, 0xc
00000068  0c0c              or al, 0xc
0000006A  0c0c              or al, 0xc
0000006C  0c0c              or al, 0xc
0000006E  0c0c              or al, 0xc
00000070  0c0c              or al, 0xc
00000072  0c0c              or al, 0xc
00000074  0c0c              or al, 0xc
00000076  0c0c              or al, 0xc
00000078  0c0c              or al, 0xc
0000007A  0c0c              or al, 0xc
0000007C  0c0c              or al, 0xc
0000007E  0c0c              or al, 0xc
00000080  0c0c              or al, 0xc
00000082  0c0c              or al, 0xc
00000084  0c0c              or al, 0xc
00000086  0c0c              or al, 0xc
00000088  0c0c              or al, 0xc
0000008A  0c0c              or al, 0xc
0000008C  0c0c              or al, 0xc
0000008E  0c0c              or al, 0xc
00000090  0c0c              or al, 0xc
00000092  0c0c              or al, 0xc
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00004f90.bin rtf-objdata-decoded RTF \objdata at offset 0x4F90 2300 bytes
SHA-256: c7ec3a942785e5ddd8f4ddd6a1790f94d0998978acdc9d1f9947fd919e77e0ed

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