cbcvebase.
CVE-2021-2135
published 2021-04-22

CVE-2021-2135: Vulnerability in the Oracle WebLogic Server product of Oracle Fusion Middleware (component: Coherence Container). Supported versions that are affected are…

PriorityP185critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
ITWEXPLOITVulnCheck KEV
Exploited in the wild
EPSS
8.37%
94.3th percentile
Vulnerability in the Oracle WebLogic Server product of Oracle Fusion Middleware (component: Coherence Container). Supported versions that are affected are 12.2.1.3.0, 12.2.1.4.0 and 14.1.1.0.0. Easily exploitable vulnerability allows unauthenticated attacker with network access via T3, IIOP to compromise Oracle WebLogic Server. Successful attacks of this vulnerability can result in takeover of Oracle WebLogic Server. CVSS 3.1 Base Score 9.8 (Confidentiality, Integrity and Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

Affected

6 ranges
VendorProductVersion rangeFixed in
oracleweblogic_server
oracleweblogic_server
oracleweblogic_server
oracle_corporationweblogic_server
oracle_corporationweblogic_server
oracle_corporationweblogic_server

Detection & IOCsextracted from sources · hover to see the quote

port7001
bytes
743320372e302e302e300a41533a31300a484c3a31390a0a
  • Detect the T3 handshake initiation string 't3 7.0.0\nAS:10\nHL:19\n\n' (hex: 743320372e302e302e300a41533a31300a484c3a31390a0a) sent over TCP to port 7001 immediately before a large serialized payload — characteristic of this exploit chain.
  • Alert on DNS/HTTP callbacks containing the strings 'rce-linux' or 'rce-window' in the request, which are the OAST beacon identifiers used by the public exploit template to confirm successful code execution.
  • Look for the Java gadget chain invoking 'java.lang.Runtime.getRuntime().exec()' via the MvelExtractor class ('com.tangosol.coherence.rest.util.extractor.MvelExtractor') in deserialized T3/IIOP payloads — the exploit embeds this as hex-encoded bytecode in the serialized stream.
  • Shodan/FOFA exposure queries for identifying internet-facing vulnerable WebLogic instances: search for cpe:"cpe:2.3:a:oracle:weblogic_server", product:"WebLogic", http.server:"WebLogic", or port:7001.
  • FOFA query to identify exposed WebLogic servers: product="WebLogic" || header="WebLogic Server".
  • ·The exploit targets T3 and IIOP protocols; organizations that have blocked T3/IIOP at the network perimeter (firewall rules on port 7001) may not be directly reachable, but the vulnerability is still present in unpatched software.
  • ·The public Nuclei template uses out-of-band (OAST/interactsh) DNS callbacks to confirm exploitation; detection based solely on inbound traffic may miss successful exploitation if OAST infrastructure is not monitored.
  • ·Affected versions are specifically 12.2.1.3.0, 12.2.1.4.0, and 14.1.1.0.0; detection rules should be scoped to these versions to reduce false positives on patched or out-of-scope deployments.

CVSS provenance

nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvdv2.07.5HIGHAV:N/AC:L/Au:N/C:P/I:P/A:P
vulncheck9.8CRITICAL
vendor_oracle9.8CRITICAL
vendor_redhat5.5MEDIUM
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