Malicious RTF — malware analysis report

Static analysis result for SHA-256 0d4dc3226f16e8d2…

MALICIOUS

RTF

64.8 KB First seen: 2019-09-30
MD5: e6032c8a2bb1af8d0a90f334e472ea56 SHA-1: 197f9ccf086ec7d3752d35516bd62f8b680cf2ee SHA-256: 0d4dc3226f16e8d24b1c5d90aa1f47bddb92cda22332ee5383e24df0bd9bc3e1
180 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object that exploits CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. The presence of \objupdate and \objdata heuristics indicates that the embedded object is designed to be activated and execute code. This is a common technique for delivering malicious payloads.

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_off00001fe9.bin rtf-objdata-decoded RTF \objdata at offset 0x1FE9 1780 bytes
SHA-256: 5d617a1eaa3c5c3ea643ad2f008ef375d928dee16390703dc6bdf985a4b1de02

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