Malicious RTF — malware analysis report

Static analysis result for SHA-256 100b0b79aaaf948d…

MALICIOUS

RTF

3.9 KB First seen: 2020-09-07
MD5: e6f73aa1f3c5deae0be1cf872c14892c SHA-1: 0c9279982bbc214e643c7e09e3d2cb3b78bcc66a SHA-256: 100b0b79aaaf948df42bb2b46ad0a6e57c67e2b2a7d91d16c225c24c77f70d2a
180 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object that triggers CVE-2017-11882 via Microsoft Equation Editor. This exploit is known to execute arbitrary code, likely to download and run a secondary payload. The document body consists of seemingly random numbers, providing no contextual lure.

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_off000000c1.bin rtf-objdata-decoded RTF \objdata at offset 0xC1 1875 bytes
SHA-256: ef97ec13056916073dd27e3b4ac5bcbbbcda38286bb49e429e773c8ae2d4acb3

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