Malicious RTF — malware analysis report

Static analysis result for SHA-256 5f4d14bf8eb8860f…

MALICIOUS

RTF

12.5 KB First seen: 2020-05-25
MD5: cd20f73152c739d52aa94031894c5ba3 SHA-1: b013558e30839b3820402eae56b8b51f0fa9677e SHA-256: 5f4d14bf8eb8860f8038779998455e063df83f43fa744c832a5be138f3332359
280 Risk Score

Malware Insights

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

The sample is an RTF document that contains an embedded OLE object. Critical heuristics indicate the exploitation of CVE-2017-11882 via Microsoft Equation Editor, a known vulnerability for client-side code execution. The ClamAV detection name further confirms this exploit. The document body is heavily obfuscated and does not provide clear user-facing content, suggesting its primary purpose is exploit delivery.

Heuristics 6

  • 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.
  • ClamAV: Rtf.Exploit.CVE_2017_11882-6584355-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Exploit.CVE_2017_11882-6584355-1
  • 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_off000014e2.bin rtf-objdata-decoded RTF \objdata at offset 0x14E2 3641 bytes
SHA-256: c56ead6348918a54aa1fd4a1761b794845fcf7788519dfe92bb4b89afb930cd0

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