WAF/SSLI – XML Vulnerabilities Subscribe to Security Advisories

Tuesday, November 27, 2018
Tuesday, November 27, 2018
Summary 

Several vulnerabilities have been resolved in ACOS that could potentially affect Web Application Firewall (WAF) and SSL Insight (SSLi) services. Accordingly, the following vulnerabilities are addressed in this document.

Item # Vulnerability ID Score Source Score Summary
1 CVE-2016-4449 CVSS 3.0 7.1 High libxml2: Inappropriate fetch of entities content
2 CVE-2016-4448 CVSS 3.0 9.8 Crit libxml2: Format string vulnerability
3 CVE-2016-4447 CVSS 3.0 7.5 High libxml2: Heap-based buffer underreads due to xmlParseName
4 CVE-2016-3705 CVSS 3.0 7.5 High libxml2: stack overflow before detecting invalid XML file
5 CVE-2016-3627 CVSS 3.0 7.5 High libxml2: stack exhaustion while parsing xml files in recovery mode
6 CVE-2016-2073 CVSS 3.0 6.5 Med libxml2: out-of-bounds read in htmlParseNameComplex()
7 CVE-2016-1840 CVSS 3.0 8.8 High libxml2: Heap-buffer-overflow in xmlFAParserPosCharGroup
8 CVE-2016-1839 CVSS 3.0 8.8 High libxml2: Heap-based buffer overread in xmlDictAddString
9 CVE-2016-1838 CVSS 3.0 8.8 High libxml2: Heap-based buffer overread in xmlPArserPrintFileContextInternal
10 CVE-2016-1837 CVSS 3.0 8.8 High libxml2: Heap use-after-free in htmlPArsePubidLiteral and htmlParseSystemiteral
11 CVE-2016-1836 CVSS 3.0 8.8 High libxml2: Heap use-after-free in xmlDictComputeFastKey
12 CVE-2016-1835 CVSS 3.0 8.8 High libxml2: Heap use-after-free in xmlSAX2AttributeNs
13 CVE-2016-1834 CVSS 3.0 8.8 High libxml2: Heap-buffer-overflow in xmlStrncat
14 CVE-2016-1833 CVSS 3.0 8.8 High libxml2: Heap-based buffer overread in htmlCurrentChar
15 CVE-2016-1762 CVSS 3.0 9.8 Crit libxml2: Heap-based buffer-overread in xmlNextChar
16 CVE-2015-8806 CVSS 3.0 7.5 High libxml2: heap-buffer overread in dict.c
17 CVE-2015-8710 CVSS 3.0 9.8 Crit libxml2: out-of-bounds memory access when parsing an unclosed HTML comment
18 CVE-2015-8317 CVSS 2.0 5.0 Med libxml2: Out-of-bounds heap read when parsing file with unfinished xml declaration
19 CVE-2015-8242 CVSS 2.0 5.8 Med libxml2: Buffer overread with HTML parser in push mode in xmlSAX2TextNode
20 CVE-2015-8241 CVSS 2.0 6.4 Med libxml2: Buffer overread with XML parser in xmlNextChar
21 CVE-2015-7942 CVSS 2.0 6.8 Med libxml2: heap-based buffer overflow in xmlParseConditionalSections()
22 CVE-2015-7941 CVSS 2.0 4.3 Med libxml2: Out-of-bounds memory access
23 CVE-2015-7500 CVSS 2.0 5.0 Med libxml2: Heap buffer overflow in xmlParseMisc
24 CVE-2015-7499 CVSS 2.0 5.0 Med libxml2: Heap-based buffer overflow in xmlGROW
25 CVE-2015-7498 CVSS 2.0 5.0 Med libxml2: Heap-based buffer overflow in xmlParseXmlDecl
26 CVE-2015-7497 CVSS 2.0 5.0 Med libxml2: Heap-based buffer overflow in xmlDictComputeFastQKey
27 CVE-2015-5312 CVSS 2.0 7.1 High libxml2: CPU exhaustion when processing specially crafted XML input
28 CVE-2015-1819 CVSS 2.0 5.0 Med libxml2: denial of service processing a crafted XML document
29 CVE-2014-3660 CVSS 2.0 5.0 Med libxml2: denial of service via recursive entity expansion
30 CVE-2014-0191 CVSS 2.0 4.3 Med libxml2: external parameter entity loaded when entity substitution is disabled
31 CVE-2013-1969 CVSS 2.0 7.5 High libxml2: multiple use-after-free flaws
32 CVE-2013-0339 CVSS 2.0 6.8 Med libxml2: CPU consumption DoS and other effects when performing string substitutions during external entities expansion
33 CVE-2013-0338 CVSS 2.0 4.3 Med libxml2: CPU consumption DoS when performing string substitutions during entities expansion
34 CVE-2012-5134 CVSS 2.0 6.8 Med libxml2: Heap-buffer-underflow in xmlParseAttValueComplex
35 A10-2018-0008 (a) A10 High libxml2: ACOS 2.7.x, 4.1.0/1/2, 4.1.4 vulnerabilities

(a) A10 Networks, Inc. assigned identifier.

Affected Releases

The table below indicates releases of ACOS exposed to these vulnerabilities and ACOS releases that address them. ACOS release families not indicated below are unaffected by these vulnerabilities.

Customers using affected ACOS releases can overcome vulnerability exposures by updating to the indicated resolved release. If the table does not list a corresponding resolved or unaffected release, then no ACOS release update is currently available.

Releases AffectedReleases Resolved or Unaffected

4.1.4 – 4.1.4-P2

4.1.4-P3

4.1.2 – 4.1.2-P4

4.1.2-P5

4.1.1 – 4.1.1-P9

4.1.1-P10

4.1.0 – 4.1.0-P11

4.1.0-P12

2.7.2 – 2.7.2-Px

4.1.0-P12, 4.1.1-P10, 4.1.4-P3

2.7.1-GR1 – 2.7.1-GR1-Px

4.1.0-P12, 4.1.1-P10, 4.1.4-P3

Workarounds and Mitigations 

In lieu of upgrading to a resolved release indicated above and recognizing the potential impact on functionality provided by the ACOS system, the following mitigations are available.

To mitigate WAF exposures, disable ACOS WAF processing and support for XML content by configuring WAF templates with configuration commands.

no xml-format-check
no xml-limit
no xml-limit
no xml-validation
no xml-xss-check
no soap-format-check

To mitigate SSLi exposures, disable ACOS SSLi processing and support for XML content by configuring SSLi templates with configuration commands.

no type xmpp
Software Updates 

Software updates that address these vulnerabilities are or will be published at the following URL:
https://www.a10networks.com/support/axseries/software-downloads

Vulnerability Details

The following table shares brief descriptions for the vulnerabilities addressed in this document.

Vulnerability IDVulnerability Description
CVE-2016-4449

XML external entity (XXE) vulnerability in the xmlStringLenDecodeEntities function in parser.c in libxml2 before 2.9.4, when not in validating mode, allows context-dependent attackers to read arbitrary files or cause a denial of service (resource consumption) via unspecified vectors.

CVE-2016-4448

Format string vulnerability in libxml2 before 2.9.4 allows attackers to have unspecified impact via format string specifiers in unknown vectors.

CVE-2016-4447

The xmlParseElementDecl function in parser.c in libxml2 before 2.9.4 allows context-dependent attackers to cause a denial of service (heap-based buffer underread and application crash) via a crafted file, involving xmlParseName.

CVE-2016-3705

The (1) xmlParserEntityCheck and (2) xmlParseAttValueComplex functions in parser.c in libxml2 2.9.3 do not properly keep track of the recursion depth, which allows context-dependent attackers to cause a denial of service (stack consumption and application crash) via a crafted XML document containing a large number of nested entity references.

CVE-2016-2073

The htmlParseNameComplex function in HTMLparser.c in libxml2 allows attackers to cause a denial of service (out-of-bounds read) via a crafted XML document.

CVE-2016-1840

Heap-based buffer overflow in the xmlFAParsePosCharGroup function in libxml2 before 2.9.4, as used in Apple iOS before 9.3.2, OS X before 10.11.5, tvOS before 9.2.1, and watchOS before 2.2.1, allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted XML document.

CVE-2016-1839

The xmlDictAddString function in libxml2 before 2.9.4, as used in Apple iOS before 9.3.2, OS X before 10.11.5, tvOS before 9.2.1, and watchOS before 2.2.1, allows remote attackers to cause a denial of service (heap-based buffer over-read) via a crafted XML document.

CVE-2016-1838

The xmlPArserPrintFileContextInternal function in libxml2 before 2.9.4, as used in Apple iOS before 9.3.2, OS X before 10.11.5, tvOS before 9.2.1, and watchOS before 2.2.1, allows remote attackers to cause a denial of service (heap-based buffer over-read) via a crafted XML document.

CVE-2016-1837

Multiple use-after-free vulnerabilities in the (1) htmlPArsePubidLiteral and (2) htmlParseSystemiteral functions in libxml2 before 2.9.4, as used in Apple iOS before 9.3.2, OS X before 10.11.5, tvOS before 9.2.1, and watchOS before 2.2.1, allow remote attackers to cause a denial of service via a crafted XML document.

CVE-2016-1836

Use-after-free vulnerability in the xmlDictComputeFastKey function in libxml2 before 2.9.4, as used in Apple iOS before 9.3.2, OS X before 10.11.5, tvOS before 9.2.1, and watchOS before 2.2.1, allows remote attackers to cause a denial of service via a crafted XML document.

CVE-2016-1835

Use-after-free vulnerability in the xmlSAX2AttributeNs function in libxml2 before 2.9.4, as used in Apple iOS before 9.3.2 and OS X before 10.11.5, allows remote attackers to cause a denial of service via a crafted XML document.

CVE-2016-1834

Heap-based buffer overflow in the xmlStrncat function in libxml2 before 2.9.4, as used in Apple iOS before 9.3.2, OS X before 10.11.5, tvOS before 9.2.1, and watchOS before 2.2.1, allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted XML document.

CVE-2016-1833

The htmlCurrentChar function in libxml2 before 2.9.4, as used in Apple iOS before 9.3.2, OS X before 10.11.5, tvOS before 9.2.1, and watchOS before 2.2.1, allows remote attackers to cause a denial of service (heap-based buffer over-read) via a crafted XML document.

CVE-2016-1762

The xmlNextChar function in libxml2 before 2.9.4 allows remote attackers to cause a denial of service (heap-based buffer over-read) via a crafted XML document.

CVE-2015-8806

dict.c in libxml2 allows remote attackers to cause a denial of service (heap-based buffer over-read and application crash) via an unexpected character immediately after the "<!DOCTYPE html" substring in a crafted HTML document.

CVE-2015-8710

The htmlParseComment function in HTMLparser.c in libxml2 allows attackers to obtain sensitive information, cause a denial of service (out-of-bounds heap memory access and application crash), or possibly have unspecified other impact via an unclosed HTML comment.

CVE-2015-8317

The xmlParseXMLDecl function in parser.c in libxml2 before 2.9.3 allows context-dependent attackers to obtain sensitive information via an (1) unterminated encoding value or (2) incomplete XML declaration in XML data, which triggers an out-of-bounds heap read.

CVE-2015-8242

The xmlSAX2TextNode function in SAX2.c in the push interface in the HTML parser in libxml2 before 2.9.3 allows context-dependent attackers to cause a denial of service (stack-based buffer over-read and application crash) or obtain sensitive information via crafted XML data.

CVE-2015-8241

The xmlNextChar function in libxml2 2.9.2 does not properly check the state, which allows context-dependent attackers to cause a denial of service (heap-based buffer over-read and application crash) or obtain sensitive information via crafted XML data.

CVE-2015-7942

The xmlParseConditionalSections function in parser.c in libxml2 does not properly skip intermediary entities when it stops parsing invalid input, which allows context-dependent attackers to cause a denial of service (out-of-bounds read and crash) via crafted XML data, a different vulnerability than CVE-2015-7941.

CVE-2015-7941

libxml2 2.9.2 does not properly stop parsing invalid input, which allows context-dependent attackers to cause a denial of service (out-of-bounds read and libxml2 crash) via crafted XML data to the (1) xmlParseEntityDecl or (2) xmlParseConditionalSections function in parser.c, as demonstrated by non-terminated entities.

CVE-2015-7500

The xmlParseMisc function in parser.c in libxml2 before 2.9.3 allows context-dependent attackers to cause a denial of service (out-of-bounds heap read) via unspecified vectors related to incorrect entities boundaries and start tags.

CVE-2015-7499

Heap-based buffer overflow in the xmlGROW function in parser.c in libxml2 before 2.9.3 allows context-dependent attackers to obtain sensitive process memory information via unspecified vectors.

CVE-2015-7498

Heap-based buffer overflow in the xmlParseXmlDecl function in parser.c in libxml2 before 2.9.3 allows context-dependent attackers to cause a denial of service via unspecified vectors related to extracting errors after an encoding conversion failure.

CVE-2015-7497

Heap-based buffer overflow in the xmlDictComputeFastQKey function in dict.c in libxml2 before 2.9.3 allows context-dependent attackers to cause a denial of service via unspecified vectors.

CVE-2015-5312

The xmlStringLenDecodeEntities function in parser.c in libxml2 before 2.9.3 does not properly prevent entity expansion, which allows context-dependent attackers to cause a denial of service (CPU consumption) via crafted XML data, a different vulnerability than CVE-2014-3660.

CVE-2015-1819

The xmlreader in libxml allows remote attackers to cause a denial of service (memory consumption) via crafted XML data, related to an XML Entity Expansion (XEE) attack.

CVE-2014-3660

parser.c in libxml2 before 2.9.2 does not properly prevent entity expansion even when entity substitution has been disabled, which allows context-dependent attackers to cause a denial of service (CPU consumption) via a crafted XML document containing a large number of nested entity references, a variant of the "billion laughs" attack.

CVE-2014-0191

The xmlParserHandlePEReference function in parser.c in libxml2 before 2.9.2, as used in Web Listener in Oracle HTTP Server in Oracle Fusion Middleware 11.1.1.7.0, 12.1.2.0, and 12.1.3.0 and other products, loads external parameter entities regardless of whether entity substitution or validation is enabled, which allows remote attackers to cause a denial of service (resource consumption) via a crafted XML document.

CVE-2013-1969

Multiple use-after-free vulnerabilities in libxml2 2.9.0 and possibly other versions might allow context-dependent attackers to cause a denial of service (crash) and possibly execute arbitrary code via vectors related to the (1) htmlParseChunk and (2) xmldecl_done functions, as demonstrated by a buffer overflow in the xmlBufGetInputBase function.

CVE-2013-0339

libxml2 through 2.9.1 does not properly handle external entities expansion unless an application developer uses the xmlSAX2ResolveEntity or xmlSetExternalEntityLoader function, which allows remote attackers to cause a denial of service (resource consumption), send HTTP requests to intranet servers, or read arbitrary files via a crafted XML document, aka an XML External Entity (XXE) issue.  NOTE: it could be argued that because libxml2 already provides the ability to disable external entity expansion, the responsibility for resolving this issue lies with application developers; according to this argument, this entry should be REJECTed and each affected application would need its own CVE.

CVE-2013-0338

libxml2 2.9.0 and earlier allows context-dependent attackers to cause a denial of service (CPU and memory consumption) via an XML file containing an entity declaration with long replacement text and many references to this entity, aka "internal entity expansion" with linear complexity.

CVE-2012-5134

Heap-based buffer underflow in the xmlParseAttValueComplex function in parser.c in libxml2 2.9.0 and earlier, as used in Google Chrome before 23.0.1271.91 and other products, allows remote attackers to cause a denial of service or possibly execute arbitrary code via crafted entities in an XML document.

A10-2017-0008

libxml2 – dated library update/upgrade

Acknowledgements 

None.

Modification History 
RevisionDateDescription
1.0
November 27, 2018

Initial Publication