Malicious RTF — malware analysis report

Static analysis result for SHA-256 cac77f792f5ff479…

MALICIOUS

RTF

3.4 KB First seen: 2019-05-16
MD5: 8b7b2b21c5ba3d8f61399165a5d76567 SHA-1: d3755a5392e1ca4de50e8137fc587effd8f4b135 SHA-256: cac77f792f5ff479b7965a13ed528c1d59b644f9aecd4b2f4f912890d8433103
120 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object with a split Equation Editor ProgID, a known method for exploiting vulnerabilities like CVE-2017-11882. The \objupdate directive forces the activation of this object, leading to arbitrary code execution. This technique is commonly used to download and execute further malicious stages.

Heuristics 3

  • 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.
  • \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_off0000003b.bin rtf-objdata-decoded RTF \objdata at offset 0x3B 1690 bytes
SHA-256: 8cec1123b1a21aff10c49fcfc21466e84d0dcb067c3676652fd318f0f7afa416

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