Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 925e42870a4909b0…

MALICIOUS

RTF / .DOC

13.9 KB First seen: 2022-06-15
MD5: 9b2eb2ef5bf42e399e0bca13dab8e667 SHA-1: 53c3b41affc8a63d2b43c68a72cc02578e3be903 SHA-256: 925e42870a4909b0d47a08c2f97d0adf93e1afe9c4913ccb691315efa69bd224
200 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The sample is an RTF document that leverages the CVE-2017-11882 vulnerability by activating an embedded Equation Editor object. This technique is commonly used to achieve arbitrary code execution. The embedded object data, when decoded, likely contains the exploit code. The presence of RTF_OBJAUTLINK and RTF_OBJUPDATE heuristics further confirms the exploitation of OLE object activation for malicious purposes.

Heuristics 5

  • Obfuscated Equation Editor ProgID + activation critical CVE related RTF_EQUATION_EDITOR
    RTF decodes to an Equation.3 ProgID from top-level \objdata hex after nested RTF junk groups are ignored, and the document also contains \objemb plus \objupdate activation. This is an obfuscated Equation Editor exploit surface associated with CVE-2017-11882 / CVE-2018-0802 families, but no exact malformed MTEF CVE primitive was recovered from this object.
  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
  • 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 2 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001fff.bin
c904f358c3a78b92152c8b12173de809b47d285af62139396536faee0fd72357		 rtf-objdata-decoded RTF \objdata at offset 0x1FFF 2058 bytes

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