Malicious RTF — malware analysis report

Static analysis result for SHA-256 66bf4d36a39b500a…

MALICIOUS

RTF

6.0 KB First seen: 2020-09-07
MD5: dcc587ad56bad64836fa15a35f125bf5 SHA-1: ba6d652108e10034458cd6ae8f5248651cc7f809 SHA-256: 66bf4d36a39b500a1820e3e280c9f94e241ed38aed577e9b5d24e69b8f7f23f6
200 Risk Score

Malware Insights

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

The RTF file contains evidence of exploitation targeting Microsoft Equation Editor, specifically related to CVE-2017-11882. The presence of OLE object data and automatic linking suggests an attempt to trigger code execution. This technique is commonly used to deliver secondary payloads, making it highly probable that this file serves as an initial vector for a more complex attack.

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_off00000cf7.bin rtf-objdata-decoded RTF \objdata at offset 0xCF7 1356 bytes
SHA-256: 8e124f15d46b1950e5c4e2b7db0d4c357383185c76cddbd9ed6de9d4ed564b07

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