Malicious RTF — malware analysis report

Static analysis result for SHA-256 dfdb893a423c44ba…

MALICIOUS

RTF

4.2 KB First seen: 2019-05-16
MD5: 548702299343a3df9b5699ed898ef6c0 SHA-1: b5d837e729510df65622681e142b60313643ba83 SHA-256: dfdb893a423c44bac3d802c282f5c723b5e842f0b3a207e843090b5241a16aeb
180 Risk Score

Malware Insights

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

The RTF document contains embedded OLE object data, specifically identified as related to the Equation Editor vulnerability (CVE-2017-11882). The presence of \objupdate directives indicates an attempt to force OLE activation, which is a common method for exploiting this vulnerability to achieve arbitrary code execution. The file is classified as malicious due to this exploit.

Heuristics 5

  • 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.
  • \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_off0000003b.bin rtf-objdata-decoded RTF \objdata at offset 0x3B 2118 bytes
SHA-256: 0be5dae3ea996cd801f539fc701447231d1bbf6948e2aad4b4b1ec7ae4c7ef2d

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