Malicious RTF — malware analysis report

Static analysis result for SHA-256 9ca3443d4778519d…

MALICIOUS

RTF

520.1 KB First seen: 2018-10-07
MD5: c095aa5cd4a80ffc7f8caaa5228d1354 SHA-1: 30f0f47a7b00f856438c9f7ee060311d0fe71191 SHA-256: 9ca3443d4778519d9770b9e94c58148fc7b1626a46e1ff9361eab16adcc7545b
240 Risk Score

Malware Insights

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

The RTF file contains an embedded OLE object that leverages the Equation Editor vulnerability (CVE-2017-11882). This vulnerability allows for the execution of arbitrary code, which is typically used to download and run a second-stage malicious payload. The presence of the Ole10Native stream and the specific CLSID associated with Equation Editor strongly indicate this exploit.

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_off00001c7f.bin rtf-objdata-decoded RTF \objdata at offset 0x1C7F 4155 bytes
SHA-256: 2edf6cb01ebed47b39eeb3f8e6afc42ec170a639f2f38793662114f105f1ad10

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