Malicious RTF — malware analysis report

Static analysis result for SHA-256 2357f50a939fb4f5…

MALICIOUS

RTF

86.5 KB First seen: 2019-05-16
MD5: ab4271ce93cc4bd8c376ebfc93af0aea SHA-1: 89b8412429364626c7874295a88446453a8b8bce SHA-256: 2357f50a939fb4f5a3efee15a842966376dccefbdc53aa6b650d9920df2b5f7b
180 Risk Score

Malware Insights

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

The RTF file contains an embedded OLE object that is specifically identified as being related to CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. The presence of `RTF_EQUATION_EDITOR` and `CVE_2017_11882_ACTIVATION_RELATED` heuristics strongly indicates exploitation of this vulnerability. The `RTF_OBJUPDATE` heuristic suggests that the embedded object is forced to activate, leading to arbitrary code execution.

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_off000060fd.bin rtf-objdata-decoded RTF \objdata at offset 0x60FD 1692 bytes
SHA-256: fec2c22f5515abd5ea5aad9ed67479569cd640db8262c2f482faabe943357c4a

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