Malicious RTF — malware analysis report

Static analysis result for SHA-256 2f96eabe43dc23d9…

MALICIOUS

RTF

22.9 KB First seen: 2020-07-24
MD5: 387c583e7e6456a6817c5bafe14f8939 SHA-1: 5de8344a56ff7894be98c237a258e6aef159b162 SHA-256: 2f96eabe43dc23d94b569f2659c7d58a257c1e9e4d2cee8b8df03d9d56168f74
200 Risk Score

Malware Insights

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

The sample is an RTF document that contains an embedded OLE object specifically identified as being related to CVE-2017-11882, a vulnerability in Microsoft Equation Editor. The presence of RTF_OBJAUTLINK and RTF_OBJUPDATE heuristics indicates that the embedded object is designed to be automatically activated, leading to code execution. This exploit is commonly used to deliver secondary 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.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001b05.bin rtf-objdata-decoded RTF \objdata at offset 0x1B05 2137 bytes
SHA-256: b090334c5b15eec0d70d1f5e248602e77f812ecf8b54f29a77b94b93b7d418a3

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