Malicious RTF — malware analysis report

Static analysis result for SHA-256 8d220aedca48ba72…

MALICIOUS

RTF

14.2 KB First seen: 2019-09-30
MD5: 924ff599762ded8164e7987dfbe7f799 SHA-1: cbec3561483c1ff2b843d3b76355035383e45997 SHA-256: 8d220aedca48ba72aeb11f58d7ca207962c6d17d9fe8c15871a243ac080c558a
200 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 is automatically linked and updated, triggering an exploit for CVE-2017-11882. This exploit is known to deliver a secondary payload, which is likely malicious. The presence of the Ole10Native stream and the specific heuristic firing for CVE-2017-11882 strongly indicate this attack vector.

Heuristics 5

  • 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.
  • 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 1 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000804.bin rtf-objdata-decoded RTF \objdata at offset 0x804 4147 bytes
SHA-256: c1e6659b0ea1ee6568fbcb18aa895ca54e52faae27e36b04baf7c39bda40ea99