Malicious RTF — malware analysis report

Static analysis result for SHA-256 308a05d933d94934…

MALICIOUS

RTF

1014.2 KB First seen: 2020-05-25
MD5: 15fd6214801c21a0d27b278d70b6fdf0 SHA-1: 6e2bc2e3de90d4793f81207ca3c93472992a2702 SHA-256: 308a05d933d94934fd2732c9c4bcd97c7a3d0a1546df804bf73cddad6ad63c28
180 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 triggers CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. This vulnerability allows for the execution of arbitrary code upon activation, likely leading to the download and execution of a second-stage payload. The file's malicious nature is confirmed by the critical heuristic firing related to Equation Editor exploitation.

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 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_off00000836.bin rtf-objdata-decoded RTF \objdata at offset 0x836 69510 bytes
SHA-256: 0b0e2f7b51c440921ee9935d468a14bbb525857c3112adbe08d58ca52a0b056f

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