Malicious RTF — malware analysis report

Static analysis result for SHA-256 97fb3b374a2cfa8e…

MALICIOUS

RTF

5.2 KB First seen: 2019-02-26
MD5: 946a2c9d940ac1351e162bc2343cfa31 SHA-1: b44a33692fce7eaad13203d46b312a3a19fe6994 SHA-256: 97fb3b374a2cfa8e947898c39850d7381adebd9b59b5a466c605d375fa6a9d9b
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 the Equation Editor vulnerability (CVE-2017-11882). The presence of `RTF_EQUATION_EDITOR` and `CVE_2017_11882_ACTIVATION_RELATED` heuristics strongly indicates this exploit. The ` tfobjupdate` directive forces the activation of this embedded object, leading to arbitrary code execution. The specific class name `eqUATiOn.3` is also indicative 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_off0000003a.bin rtf-objdata-decoded RTF \objdata at offset 0x3A 2508 bytes
SHA-256: 0287d1f6a6ccfe417229ba050b20a02dec148b3e0a9b9b7e3428e11fb4ff1f92

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