CVE-2023-36851

published 2023-09-27

CVE-2023-36851: A Missing Authentication for Critical Function vulnerability in Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to…

Priority P1 83 medium 5.3 CVSS 3.1

AV N AC L PR N UI N S U C N I L A N

KEV ITW

A Missing Authentication for Critical Function vulnerability in Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause limited impact to the file system integrity.

With a specific request to

webauth_operation.php

that doesn't require authentication, an attacker is able to upload and download arbitrary files via J-Web, leading to a loss of

integrity or confidentiality, which may allow chaining to other vulnerabilities.

This issue affects Juniper Networks Junos OS on SRX Series:

*

21.2 versions prior to 21.2R3-S8;
* 21.4

versions prior to

21.4R3-S6;
* 22.1

versions prior to

22.1R3-S5;
* 22.2

versions prior to

22.2R3-S3;
* 22.3

versions prior to

22.3R3-S2;
* 22.4 versions prior to 22,4R2-S2, 22.4R3;
* 23.2 versions prior to

23.2R1-S2, 23.2R2.

Affected

17 ranges

Vendor	Product	Version range	Fixed in
juniper	j-web	—	—
juniper	junos	—	—
juniper	junos	—	—
juniper	junos	—	—
juniper	junos	—	—
juniper	junos	—	—
juniper	junos	—	—
juniper	junos	—	—
juniper	junos_os	—	—
juniper	srx_series	—	—
juniper_networks	junos_os	>= 21.2 < 21.2R3-S8	21.2R3-S8
juniper_networks	junos_os	>= 21.4 < 21.4R3-S6	21.4R3-S6
juniper_networks	junos_os	>= 22.1 < 22.1R3-S5	22.1R3-S5
juniper_networks	junos_os	>= 22.2 < 22.2R3-S3	22.2R3-S3
juniper_networks	junos_os	>= 22.3 < 22.3R3-S2	22.3R3-S2
juniper_networks	junos_os	>= 22.4 < 22.4R2-S2, 22.4R3	22.4R2-S2, 22.4R3
juniper_networks	junos_os	>= 23.2 < 23.2R1-S2, 23.2R2	23.2R1-S2, 23.2R2

Detection & IOCs extracted from sources · hover to see the quote

path /webauth_operation.php↗

command rs=do_upload

snort

alert http any any -> [$HOME_NET,$HTTP_SERVERS] any (msg:"ET EXPLOIT Junos OS - Unauthenticated Arbitrary File Upload Attempt (CVE-2023-36851)"; flow:established,to_server; flowbits:set,ET.CVE-2023-36851; http.method; content:"POST"; http.uri; content:"/webauth_operation.php"; fast_pattern; http.request_body; content:"rs=do_upload"; nocase; content:"rsargs"; nocase; content:"fileName"; nocase; content:"fileData"; nocase; content:"csize"; nocase; reference:url,supportportal.juniper.net/s/article/2023-08-Out-of-Cycle-Security-Bulletin-Junos-OS-SRX-Series-and-EX-Series-Multiple-vulnerabilities-in-J-Web-can-be-combined-to-allow-a-preAuth-Remote-Code-Execution; reference:url,labs.watchtowr.com/cve-2023-36844-and-friends-rce-in-juniper-firewalls/; reference:cve,2023-36846; reference:cve,2023-36847; classtype:attempted-admin; sid:2047867; rev:2; metadata:affected_product JunOS, attack_target Networking_Equipment, tls_state TLSDecrypt, created_at 2023_09_01, cve CVE_2023_36851, deployment Perimeter, deployment Internal, deployment SSLDecrypt, performance_impact Low, confidence High, signature_severity Major, tag CISA_KEV, updated_at 2024_03_12, reviewed_at 2023_09_01; target:dest_ip;)

snort

alert http [$HOME_NET,$HTTP_SERVERS] any -> any any (msg:"ET EXPLOIT Junos OS - Successful Unauthenticated Arbitrary File Upload Attempt (CVE-2023-36851)"; flow:established,to_client; flowbits:isset,ET.CVE-2023-36851; http.stat_code; content:"200"; http.response_body; content:"|22|converted_fileName|22|"; fast_pattern; content:"0|3a 20|"; distance:0; content:"|22|original_fileName|22|"; reference:url,supportportal.juniper.net/s/article/2023-08-Out-of-Cycle-Security-Bulletin-Junos-OS-SRX-Series-and-EX-Series-Multiple-vulnerabilities-in-J-Web-can-be-combined-to-allow-a-preAuth-Remote-Code-Execution; reference:url,labs.watchtowr.com/cve-2023-36844-and-friends-rce-in-juniper-firewalls/; reference:cve,2023-36846; reference:cve,2023-36847; classtype:successful-admin; sid:2047868; rev:2; metadata:affected_product JunOS, attack_target Networking_Equipment, tls_state TLSDecrypt, created_at 2023_09_01, cve CVE_2023_36851, deployment Perimeter, deployment Internal, deployment SSLDecrypt, performance_impact Low, confidence High, signature_severity Major, tag CISA_KEV, updated_at 2024_03_12, reviewed_at 2023_09_01; target:src_ip;)

bytes

|22|converted_fileName|22|

• → Exploit traffic targets J-Web via unauthenticated HTTP POST to /webauth_operation.php with body parameters rs=do_upload, rsargs, fileName, fileData, and csize — no authentication required.
• → Successful exploitation is confirmed by an HTTP 200 response containing JSON keys 'converted_fileName' and 'original_fileName' in the response body.
• → CVE-2023-36851 is commonly chained with CVE-2023-36844, CVE-2023-36846, and CVE-2023-36847 to achieve pre-auth Remote Code Execution on Juniper SRX/EX Series devices.

• · Both Snort rules include 'tls_state TLSDecrypt' metadata, meaning they will only fire on TLS-encrypted J-Web traffic if SSL/TLS inspection (decryption) is enabled on the monitoring sensor.

CVSS provenance

nvd v3.1 5.3 MEDIUM CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

vulncheck 5.3 MEDIUM

cisa 5.3 MEDIUM

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