Malicious RTF — malware analysis report

Static analysis result for SHA-256 b35a2c782ddaa8f5…

MALICIOUS

RTF

16.9 KB First seen: 2018-10-07
MD5: 8b590c21b4034423618686be3dc9c7ba SHA-1: 02aed33a92ad4b0c1110c6023308cd0f978ebdb5 SHA-256: b35a2c782ddaa8f5d467b2abbb4ae12e0553f09061947f02f23d9ae17d58ff75
260 Risk Score

Malware Insights

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

The RTF file contains an embedded OLE object with a CLSID indicative of Equation Editor, specifically triggering the CVE-2017-11882 vulnerability. This exploit is designed to execute arbitrary code, likely leading to the download and execution of a secondary payload. The presence of the Ole10Native stream and the objupdate directive further confirm the exploitation attempt.

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
  • 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.
  • 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_off00000cda.bin rtf-objdata-decoded RTF \objdata at offset 0xCDA 4671 bytes
SHA-256: 487cc3bca7e246ee41d582c70bbf08f1619b4e3cc94f808a66e8625158a39e33

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