Malicious RTF — malware analysis report

Static analysis result for SHA-256 e338fd3b0a3a4d80…

MALICIOUS

RTF

10.3 KB First seen: 2019-04-18
MD5: 9a2d1994263ac988721f03b553092314 SHA-1: d3bee2cc04827dca1579d2b5e8e5eb6b556af81d SHA-256: e338fd3b0a3a4d8003ce79170b0b94710cca731d64a3490b330eba736e74e4a8
180 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object that triggers the CVE-2017-11882 vulnerability in Microsoft Equation Editor. This exploit is known to be used for arbitrary code execution, typically to download and run a second-stage payload. The presence of the Equation Editor ProgID 'EQUaTioN.3' is a strong indicator of 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_off0000190f.bin rtf-objdata-decoded RTF \objdata at offset 0x190F 2055 bytes
SHA-256: ed6220780afbc1eb1ce262d9f586a4df7f32e0f8d2edebdf52f09d7bbce0e1cc

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