Detections
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Oracle Linux 8 : squid:4 (ELSA-2020-4743)

critical Nessus Plugin ID 180917

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Synopsis

The remote Oracle Linux host is missing one or more security updates.

Description

The remote Oracle Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the ELSA-2020-4743 advisory.

 - An issue was discovered in Squid before 4.10. It allows a crafted FTP server to trigger disclosure of sensitive information from heap memory, such as information associated with other users' sessions or non- Squid processes. (CVE-2019-12528)

 - An issue was discovered in Squid before 4.10. Due to incorrect buffer management, a remote client can cause a buffer overflow in a Squid instance acting as a reverse proxy. (CVE-2020-8450)

 - An issue was discovered in http/ContentLengthInterpreter.cc in Squid before 4.12 and 5.x before 5.0.3. A Request Smuggling and Poisoning attack can succeed against the HTTP cache. The client sends an HTTP request with a Content-Length header containing +\ - or an uncommon shell whitespace character prefix to the length field-value. (CVE-2020-15049)

 - Squid before 4.13 and 5.x before 5.0.4 allows a trusted peer to perform Denial of Service by consuming all available CPU cycles during handling of a crafted Cache Digest response message. This only occurs when cache_peer is used with the cache digests feature. The problem exists because peerDigestHandleReply() livelocking in peer_digest.cc mishandles EOF. (CVE-2020-24606)

 - An issue was discovered in Squid before 4.10. Due to incorrect input validation, it can interpret crafted HTTP requests in unexpected ways to access server resources prohibited by earlier security filters.
 (CVE-2020-8449)

 - An issue was discovered in Squid through 4.7. When Squid is parsing ESI, it keeps the ESI elements in ESIContext. ESIContext contains a buffer for holding a stack of ESIElements. When a new ESIElement is parsed, it is added via addStackElement. addStackElement has a check for the number of elements in this buffer, but it's off by 1, leading to a Heap Overflow of 1 element. The overflow is within the same structure so it can't affect adjacent memory blocks, and thus just leads to a crash while processing.
 (CVE-2019-12521)

 - An issue was discovered in Squid before 4.9. When handling a URN request, a corresponding HTTP request is made. This HTTP request doesn't go through the access checks that incoming HTTP requests go through. This causes all access checks to be bypassed and allows access to restricted HTTP servers, e.g., an attacker can connect to HTTP servers that only listen on localhost. (CVE-2019-12523)

 - An issue was discovered in Squid through 4.7. When handling requests from users, Squid checks its rules to see if the request should be denied. Squid by default comes with rules to block access to the Cache Manager, which serves detailed server information meant for the maintainer. This rule is implemented via url_regex. The handler for url_regex rules URL decodes an incoming request. This allows an attacker to encode their URL to bypass the url_regex check, and gain access to the blocked resource. (CVE-2019-12524)

 - An issue was discovered in Squid before 4.9. URN response handling in Squid suffers from a heap-based buffer overflow. When receiving data from a remote server in response to an URN request, Squid fails to ensure that the response can fit within the buffer. This leads to attacker controlled data overflowing in the heap. (CVE-2019-12526)

 - An issue was discovered in Squid 2.x through 2.7.STABLE9, 3.x through 3.5.28, and 4.x through 4.7. When Squid is configured to use Basic Authentication, the Proxy-Authorization header is parsed via uudecode.
 uudecode determines how many bytes will be decoded by iterating over the input and checking its table. The length is then used to start decoding the string. There are no checks to ensure that the length it calculates isn't greater than the input buffer. This leads to adjacent memory being decoded as well. An attacker would not be able to retrieve the decoded data unless the Squid maintainer had configured the display of usernames on error pages. (CVE-2019-12529)

 - Squid before 4.9, when certain web browsers are used, mishandles HTML in the host (aka hostname) parameter to cachemgr.cgi. (CVE-2019-18860)

 - An issue was discovered in Squid before 4.12 and 5.x before 5.0.3. Due to use of a potentially dangerous function, Squid and the default certificate validation helper are vulnerable to a Denial of Service when opening a TLS connection to an attacker-controlled server for HTTPS. This occurs because unrecognized error values are mapped to NULL, but later code expects that each error value is mapped to a valid error string. (CVE-2020-14058)

 - An issue was discovered in Squid through 4.7 and 5. When receiving a request, Squid checks its cache to see if it can serve up a response. It does this by making a MD5 hash of the absolute URL of the request.
 If found, it servers the request. The absolute URL can include the decoded UserInfo (username and password) for certain protocols. This decoded info is prepended to the domain. This allows an attacker to provide a username that has special characters to delimit the domain, and treat the rest of the URL as a path or query string. An attacker could first make a request to their domain using an encoded username, then when a request for the target domain comes in that decodes to the exact URL, it will serve the attacker's HTML instead of the real HTML. On Squid servers that also act as reverse proxies, this allows an attacker to gain access to features that only reverse proxies can use, such as ESI. (CVE-2019-12520)

 - Due to incorrect string termination, Squid cachemgr.cgi 4.0 through 4.7 may access unallocated memory. On systems with memory access protections, this can cause the CGI process to terminate unexpectedly, resulting in a denial of service for all clients using it. (CVE-2019-12854)

 - An issue was discovered in Squid 3.x and 4.x through 4.8. Due to incorrect input validation, there is a heap-based buffer overflow that can result in Denial of Service to all clients using the proxy. Severity is high due to this vulnerability occurring before normal security checks; any remote client that can reach the proxy port can trivially perform the attack via a crafted URI scheme. (CVE-2019-18676)

 - An issue was discovered in Squid 3.x and 4.x through 4.8 when the append_domain setting is used (because the appended characters do not properly interact with hostname length restrictions). Due to incorrect message processing, it can inappropriately redirect traffic to origins it should not be delivered to.
 (CVE-2019-18677)

 - An issue was discovered in Squid 3.x and 4.x through 4.8. It allows attackers to smuggle HTTP requests through frontend software to a Squid instance that splits the HTTP Request pipeline differently. The resulting Response messages corrupt caches (between a client and Squid) with attacker-controlled content at arbitrary URLs. Effects are isolated to software between the attacker client and Squid. There are no effects on Squid itself, nor on any upstream servers. The issue is related to a request header containing whitespace between a header name and a colon. (CVE-2019-18678)

 - An issue was discovered in Squid 2.x, 3.x, and 4.x through 4.8. Due to incorrect data management, it is vulnerable to information disclosure when processing HTTP Digest Authentication. Nonce tokens contain the raw byte value of a pointer that sits within heap memory allocation. This information reduces ASLR protections and may aid attackers isolating memory areas to target for remote code execution attacks.
 (CVE-2019-18679)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Solution

Update the affected libecap, libecap-devel and / or squid packages.

See Also

https://linux.oracle.com/errata/ELSA-2020-4743.html

Plugin Details

Severity: Critical

ID: 180917

File Name: oraclelinux_ELSA-2020-4743.nasl

Version: 1.0

Type: local

Agent: unix

Published: 9/7/2023

Updated: 9/7/2023

Supported Sensors: Continuous Assessment, Frictionless Assessment Agent, Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5.9

CVSS v2

Risk Factor: High

Base Score: 7.5

Temporal Score: 5.5

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P

CVSS Score Source: CVE-2020-8450

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 8.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

CVSS Score Source: CVE-2019-12526

Vulnerability Information

CPE: p-cpe:/a:oracle:linux:libecap-devel, p-cpe:/a:oracle:linux:squid, cpe:/o:oracle:linux:8, p-cpe:/a:oracle:linux:libecap

Required KB Items: Host/OracleLinux, Host/RedHat/release, Host/RedHat/rpm-list, Host/local_checks_enabled

Exploit Ease: No known exploits are available

Patch Publication Date: 11/10/2020

Vulnerability Publication Date: 7/11/2019

Reference Information

CVE: CVE-2019-12520, CVE-2019-12521, CVE-2019-12523, CVE-2019-12524, CVE-2019-12526, CVE-2019-12528, CVE-2019-12529, CVE-2019-12854, CVE-2019-18676, CVE-2019-18677, CVE-2019-18678, CVE-2019-18679, CVE-2019-18860, CVE-2020-14058, CVE-2020-15049, CVE-2020-24606, CVE-2020-8449, CVE-2020-8450