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2021-04 Security Bulletin: Junos OS: Multiple HTTP/2 vulnerabilities are resolved in remote procedure calls using gRPC remote procedure calls (gRPC) framework

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Article ID: JSA11167 SECURITY_ADVISORIES Last Updated: 14 Apr 2021Version: 1.0
Product Affected:
This issue affects Junos OS 16.1R3 and later versions prior to 18.3R2-S4, 18.4, 19.1, 19.2, 19.3.
Problem:

Multiple vulnerabilities have been resolved in Juniper Networks Junos OS by fixing vulnerabilities in third party gRPC remote procedure calls (gRPC) stack.

gRPC uses HTTP/2 as its transfer protocol and provides the request/response interface between the Junos extension toolkit (JET) service daemon (JSD) and the on-box or off-box application.

These attack vectors can be used to launch Denial of Service (DoS) attacks against servers that support HTTP/2 communication. Continued receipt and processing of these packets will create a sustained Denial of Service (DoS) condition.

This issue affects:

Juniper Networks Junos OS

  • 16.1R3 and later versions prior to 18.3R2-S4, 18.3R3-S3;
  • 18.4 versions prior to 18.4R1-S8, 18.4R2-S5, 18.4R3-S4;
  • 19.1 versions prior to 19.1R1-S6, 19.1R2-S2, 19.1R3-S2;
  • 19.2 versions prior to 19.2R1-S5, 19.2R2;

This issue does not affect:

Juniper Networks Junos OS versions prior to 16.1R3.

The examples of the config stanza affected by this issue:

[system services extension-service request-response grpc]

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was discovered during a external security research.

Important security issues resolved include:
 

CVE CVSS Summary
CVE-2019-9511 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) “Data Dribble”: The attacker requests a large amount of data from a specified resource over multiple streams. They manipulate window size and stream priority to force the server to queue the data in 1-byte chunks. Depending on how efficiently this data is queued, this can consume excess CPU, memory, or both, potentially leading to a denial of service.
CVE-2019-9512 7.5 (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) "Ping Flood": The attacker sends continual pings to an HTTP/2 peer, causing the peer to build an internal queue of responses. Depending on how efficiently this data is queued, this can consume excess CPU, memory, or both, potentially leading to a denial of service.
CVE-2019-9513 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) “Resource Loop”: The attacker creates multiple request streams and continually shuffles the priority of the streams in a way that causes substantial churn to the priority tree. This can consume excess CPU, potentially leading to a denial of service.
CVE-2019-9514 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) “Reset Flood”: The attacker opens a number of streams and sends an invalid request over each stream that should solicit a stream of RST_STREAM frames from the peer. Depending on how the peer queues the RST_STREAM frames, this can consume excess memory, CPU, or both, potentially leading to a denial of service.
CVE-2019-9515 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) “Settings Flood”: The attacker sends a stream of SETTINGS frames to the peer. Since the RFC requires that the peer reply with one acknowledgement per SETTINGS frame, an empty SETTINGS frame is almost equivalent in behavior to a ping. Depending on how efficiently this data is queued, this can consume excess CPU, memory, or both, potentially leading to a denial of service.
CVE-2019-9516 6.5 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) “0-Length Headers Leak”: The attacker sends a stream of headers with a 0-length header name and 0-length header value, optionally Huffman encoded into 1-byte or greater headers. Some implementations allocate memory for these headers and keep the allocation alive until the session dies. This can consume excess memory, potentially leading to a denial of service.
CVE-2019-9517 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) “Internal Data Buffering”: The attacker opens the HTTP/2 window so the peer can send without constraint; however, they leave the TCP window closed so the peer cannot actually write (many of) the bytes on the wire. The attacker then sends a stream of requests for a large response object. Depending on how the servers queue the responses, this can consume excess memory, CPU, or both, potentially leading to a denial of service.
CVE-2019-9518 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) “Empty Frames Flood”: The attacker sends a stream of frames with an empty payload and without the end-of-stream flag. These frames can be DATA, HEADERS, CONTINUATION and/or PUSH_PROMISE. The peer spends time processing each frame disproportionate to attack bandwidth. This can consume excess CPU, potentially leading to a denial of service.
Solution:

The following software releases have been updated to resolve this specific issue: Junos OS: 18.3R2-S4, 18.3R3-S3, 18.4R1-S8, 18.4R2-S5, 18.4R3-S4, 19.1R1-S6, 19.1R2-S2, 19.1R3-S2, 19.2R1-S5, 19.2R2, 19.3R2, 19.4R1, and all subsequent releases.

This issue is being tracked as 1454794.

Workaround:

Administrator can disable gRPC configuration under "set system services extension-service request-response grpc" hierarchy.

Implementation:
Software releases or updates are available for download at https://support.juniper.net/support/downloads/
Modification History:
2021-04-14: Initial Publication.
CVSS Score:
7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Severity Level:
High
Severity Assessment:
Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."

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