Malicious RTF — malware analysis report

Static analysis result for SHA-256 24b769b89e2454bf…

MALICIOUS

RTF

375.2 KB First seen: 2019-01-20
MD5: b764336bb9bc11d582ed6de74ef2babe SHA-1: 3d5cee9a49dc1a8d74476eda56c73868ec9b79e1 SHA-256: 24b769b89e2454bf53f4e54bda5ef8e570650c6b184dff9248b7dfedf2615539
200 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 leverages a known vulnerability in Microsoft Equation Editor (CVE-2017-11882) for execution. The object's ProgID 'eQUatIoN.3' is indicative of this exploit. The primary goal is likely to download and execute a secondary payload, although the specific payload and delivery mechanism are not detailed in the provided evidence.

Heuristics 5

  • Obfuscated Equation Editor ProgID + activation critical CVE related RTF_EQUATION_EDITOR
    RTF decodes to an Equation.3 ProgID from top-level \objdata hex after nested RTF junk groups are ignored, and the document also contains \objemb plus \objupdate activation. This is an obfuscated Equation Editor exploit surface associated with CVE-2017-11882 / CVE-2018-0802 families, but no exact malformed MTEF CVE primitive was recovered from this object.
  • 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_off00001cbf.bin rtf-objdata-decoded RTF \objdata at offset 0x1CBF 2199 bytes
SHA-256: 7938b8cd884e86e45a5dc0e56ef1a41536fa3593e3c05c4c6be8357b6a887a46

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