Malicious RTF — malware analysis report

Static analysis result for SHA-256 5f43fbb6c06650bb…

MALICIOUS

RTF

16.2 KB First seen: 2020-07-02
MD5: 795e62136086c16560b83fc9bd29d6cb SHA-1: de6f0c5a308c5f1e4d7aaf4c98378c2ffea01094 SHA-256: 5f43fbb6c06650bb2781c4d8043b0b83b11e0dd77a9bc262fc2509f2e622bf68
180 Risk Score

Malware Insights

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

The sample is an RTF document containing an embedded OLE object that triggers CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. This exploit allows for arbitrary code execution, which is typically used to download and run a second-stage payload. The specific 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_off0000101c.bin rtf-objdata-decoded RTF \objdata at offset 0x101C 1732 bytes
SHA-256: 2c8e665fc706bb4bacf57f2ae308e6cb126e06ae2b72bee92ef44c7552b4e206

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