Malicious RTF — malware analysis report

Static analysis result for SHA-256 a789c2ec4cd8cf33…

MALICIOUS

RTF

8.2 KB First seen: 2019-09-30
MD5: 39d2fba8dfd074ac6c03784527a98b7a SHA-1: 2c384316f15d5d12837d3ea2d313289d3300dd86 SHA-256: a789c2ec4cd8cf33a73536eec9770c79a6c69a073803205b2dadc3ee1f41f7c6
180 Risk Score

Malware Insights

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

The RTF file contains embedded OLE object data, specifically triggering critical heuristics for CVE-2017-11882 related to the Equation Editor. This indicates the file is designed to exploit this vulnerability for client-side code execution. The presence of ".objupdate" further suggests an attempt to force OLE object activation. Given the nature of the exploit, it is highly likely this file was delivered as a spearphishing attachment.

Heuristics 4

  • Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR
    Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
  • CVE-2017-11882 — Equation Editor FONT record overflow critical CVE likely CVE_2017_11882
    Equation Editor MTEF contains an overlong FONT typeface field, the vulnerable copy primitive for CVE-2017-11882. This is stronger evidence than the Equation Editor CLSID alone because it identifies the malformed record that drives code execution in EQNEDT32.EXE.
  • \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_off00000033.bin rtf-objdata-decoded RTF \objdata at offset 0x33 4144 bytes
SHA-256: 075f771bf40c1af913499901e1badcb0a520117b1f962dea9a9b9b0325036207

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