Malicious RTF — malware analysis report

Static analysis result for SHA-256 ca8774ef30d8383c…

MALICIOUS

RTF

16.9 KB First seen: 2018-10-07
MD5: 7775cd945b6f3b1c5220da5c713cab05 SHA-1: 3f6fd419266b91ec5afce94979f0f1802baea4d8 SHA-256: ca8774ef30d8383c3886b251f6423689ddb4b7fc339e021fe1852ef6f14d5cba
240 Risk Score

Malware Insights

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

The RTF file contains critical heuristics indicating the exploitation of CVE-2017-11882 via an embedded Equation Editor OLE object. This exploit is commonly used to deliver secondary payloads. The presence of Ole10Native stream data further supports this finding. No document body or script content was available for analysis, but the exploit itself is sufficient evidence of malicious intent.

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.
  • \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
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000cd6.bin rtf-objdata-decoded RTF \objdata at offset 0xCD6 4671 bytes
SHA-256: d31346dd49b53ae04e359e7b219bdb4e570673f67a533a8ec6e6b847fb05c5c7

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