Malicious RTF — malware analysis report

Static analysis result for SHA-256 c3b532be13b6c325…

MALICIOUS

RTF

11.6 KB First seen: 2018-07-27
MD5: da13ff55af42ae95ab3e33e15c270d6b SHA-1: a3d3a67bd3cbbd6bce9d603764b0755f30a18d29 SHA-256: c3b532be13b6c3255348f7a9bf4e7b787b30a260978b8cb8eb61f6c6412bbc01
320 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 identified as a payload for Equation Editor, strongly indicating exploitation of CVE-2017-11882. This vulnerability allows for client-side execution of arbitrary code, likely to download and run a secondary malicious payload. The file's structure and heuristic firings directly point to this exploit.

Heuristics 7

  • 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
  • Equation Editor Ole10Native payload — CVE-2017-11882 likely critical CVE likely CVE_2017_11882_EQUATION_OLE10NATIVE
    RTF decodes to an activated Microsoft Equation 3.0 OLE storage whose payload is a high-entropy Ole10Native stream rather than normal Equation Native/MTEF data. This is a weaponized Equation Editor RCE delivery shape consistent with CVE-2017-11882/CVE-2018-0802.
  • Ole10Native stream in RTF OLE object high CVE related RTF_OLE10NATIVE_STREAM
    RTF contains an embedded OLE object with an Ole10Native stream. This is a strong payload-container signal and is related to Word/OLE exploit delivery, but it is not specific enough on its own to assign a CVE.
  • 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_off00000a2e.bin rtf-objdata-decoded RTF \objdata at offset 0xA2E 4643 bytes
SHA-256: 0427e8c105601cb6da6638970ee3a93853210760c4e8a142262aae2f8a3b6c93

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