Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 25557ec98c39a65e…

MALICIOUS

RTF / .DOC

10.0 KB
MD5: 4d6267883334e7517461fab028ca5c3c SHA-1: 568ff7498c85d581cea530194dd9e1b1c1a568f6 SHA-256: 25557ec98c39a65ecddeb3f5c0b3d1e1aaa4d3e07a57e3a3f7458401b2407798
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The sample is an RTF document that leverages the Equation Editor vulnerability (CVE-2017-11882) to achieve code execution. The presence of OLE object data and specific heuristics like RTF_EQUATION_EDITOR and CVE_2017_11882_ACTIVATION_RELATED strongly indicate this exploit. The primary goal appears to be the execution of a secondary payload, typical of a downloader or initial access stage.

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.
  • \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
  • 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_off000013f5.bin
11f358c7d6fabe54f958c91a9dd4fdb303d553e7b61ce10c4eb713bfeae0e24d		 rtf-objdata-decoded RTF \objdata at offset 0x13F5 1982 bytes

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