Multiple security issues were discovered in the Squid proxy caching server, which could result in the bypass of security filters, information disclosure, the execution of arbitrary code or denial of service.

According to the versions of the squid packages installed, the EulerOS installation on the remote host is affected by the following vulnerabilities :

  - 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 through 4.7. When     handling the tag esi:when when ESI is enabled, Squid     calls ESIExpression::Evaluate. This function uses a     fixed stack buffer to hold the expression while it's     being evaluated. When processing the expression, it     could either evaluate the top of the stack, or add a     new member to the stack. When adding a new member,     there is no check to ensure that the stack won't     overflow.(CVE-2019-12519)

  - 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 5.0.2. A remote     attacker can replay a sniffed Digest Authentication     nonce to gain access to resources that are otherwise     forbidden. This occurs because the attacker can     overflow the nonce reference counter (a short integer).
    Remote code execution may occur if the pooled token     credentials are freed (instead of replayed as valid     credentials).(CVE-2020-11945)

  - 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 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 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 Squid before 4.10. Due to     incorrect input validation, the NTLM authentication     credentials parser in ext_lm_group_acl may write to     memory outside the credentials buffer. On systems with     memory access protections, this can result in the     helper process being terminated unexpectedly. This     leads to the Squid process also terminating and a     denial of service for all clients using the     proxy.(CVE-2020-8517)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The remote SUSE Linux SLES11 host has a package installed that is affected by multiple vulnerabilities as referenced in the SUSE-SU-2020:14460-1 advisory.

  - An issue was discovered in Squid through 4.7. When handling the tag esi:when when ESI is enabled, Squid     calls ESIExpression::Evaluate. This function uses a fixed stack buffer to hold the expression while it's     being evaluated. When processing the expression, it could either evaluate the top of the stack, or add a     new member to the stack. When adding a new member, there is no check to ensure that the stack won't     overflow. (CVE-2019-12519)

  - 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)

  - 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 3.3.9 through 3.5.28 and 4.x through 4.7. When Squid is configured to use     Digest authentication, it parses the header Proxy-Authorization. It searches for certain tokens such as     domain, uri, and qop. Squid checks if this token's value starts with a quote and ends with one. If so, it     performs a memcpy of its length minus 2. Squid never checks whether the value is just a single quote     (which would satisfy its requirements), leading to a memcpy of its length minus 1. (CVE-2019-12525)

  - 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 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 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)

  - The cachemgr.cgi web module of Squid through 4.7 has XSS via the user_name or auth parameter.
    (CVE-2019-13345)

  - 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)

  - 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 5.0.2. A remote attacker can replay a sniffed Digest     Authentication nonce to gain access to resources that are otherwise forbidden. This occurs because the     attacker can overflow the nonce reference counter (a short integer). Remote code execution may occur if     the pooled token credentials are freed (instead of replayed as valid credentials). (CVE-2020-11945)

  - An issue was discovered in Squid 5.x before 5.0.3. Due to an Incorrect Synchronization, a Denial of     Service can occur when processing objects in an SMP cache because of an Ipc::Mem::PageStack::pop ABA     problem during access to the memory page/slot management list. (CVE-2020-14059)

  - 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)

  - 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 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 Squid before 4.10. Due to incorrect input validation, the NTLM authentication     credentials parser in ext_lm_group_acl may write to memory outside the credentials buffer. On systems with     memory access protections, this can result in the helper process being terminated unexpectedly. This leads     to the Squid process also terminating and a denial of service for all clients using the proxy.
    (CVE-2020-8517)

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

This update for squid to version 4.11 fixes the following issues :

CVE-2020-11945: Fixed a potential remote code execution vulnerability when using HTTP Digest Authentication (bsc#1170313).

CVE-2019-12519, CVE-2019-12521: Fixed incorrect buffer handling that can result in cache poisoning, remote execution, and denial of service attacks when processing ESI responses (bsc#1169659).

CVE-2020-8517: Fixed a possible denial of service caused by incorrect buffer management ext_lm_group_acl when processing NTLM Authentication credentials (bsc#1162691).

CVE-2019-12528: Fixed possible information disclosure when translating FTP server listings into HTTP responses (bsc#1162689).

CVE-2019-18860: Fixed handling of invalid domain names in cachemgr.cgi (bsc#1167373).

Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

This update for squid to version 4.11 fixes the following issues :

  - CVE-2020-11945: Fixed a potential remote code execution     vulnerability when using HTTP Digest Authentication     (bsc#1170313).

  - CVE-2019-12519, CVE-2019-12521: Fixed incorrect buffer     handling that can result in cache poisoning, remote     execution, and denial of service attacks when processing     ESI responses (bsc#1169659).

  - CVE-2020-8517: Fixed a possible denial of service caused     by incorrect buffer management ext_lm_group_acl when     processing NTLM Authentication credentials     (bsc#1162691).

  - CVE-2019-12528: Fixed possible information disclosure     when translating FTP server listings into HTTP responses     (bsc#1162689).

  - CVE-2019-18860: Fixed handling of invalid domain names     in cachemgr.cgi (bsc#1167373).

This update was imported from the SUSE:SLE-15:Update update project.

ID	名称	产品	系列	发布时间	最近更新时间	严重程度
136430	Debian DSA-4682-1 : squid - security update	Nessus	Debian Local Security Checks	2020/5/11	2024/3/13	critical
140894	EulerOS 2.0 SP3 : squid (EulerOS-SA-2020-2127)	Nessus	Huawei Local Security Checks	2020/9/28	2022/5/12	critical
150657	SUSE SLES11 Security Update : squid3 (SUSE-SU-2020:14460-1)	Nessus	SuSE Local Security Checks	2021/6/10	2023/12/26	critical
136081	SUSE SLES12 Security Update : squid (SUSE-SU-2020:1134-1)	Nessus	SuSE Local Security Checks	2020/4/29	2024/3/14	critical
136452	openSUSE Security Update : squid (openSUSE-2020-623)	Nessus	SuSE Local Security Checks	2020/5/11	2024/3/13	critical

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