CyberSecBulletin
CVE-2017-0022Exploited in the wildNVD status: Analyzed

Microsoft XML Core Services Information Disclosure

Published Updated By the CyberSecBulletin desk

CVE-2017-0022 is a medium-severity improper restriction of operations within the bounds of a memory buffer vulnerability in XML Core Services from Microsoft, with a CVSS 3.1 base score of 6.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. CISA added it to the Known Exploited Vulnerabilities catalogue on May 24, 2022, which means attacks have been observed in the wild.

Patch now

Attackers are already exploiting this vulnerability, according to CISA.

What to do

  1. Check which version of XML Core Services you run against the affected versions below, and install the vendor's latest release.
  2. CISA's required action: Apply updates per vendor instructions.
  3. Read the advisory on portal.msrc.microsoft.com for workarounds and exact fixed builds.
  4. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
  5. Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.

Affected products and versions

VendorProductAffected versionsFixed in
MicrosoftXML Core ServicesNot specified in the recordNot stated
MicrosoftWindows 8.1Not specified in the recordNot stated
MicrosoftWindows Server 2008r2Not stated
MicrosoftWindows Server 2012r2Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
RequiredA user must take an action such as opening a file or link.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
NoneNothing can be modified.
Availability
NoneAvailability is not affected.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.16.5MediumNVD
CVSS 3.16.5MediumCISA (ADP)
CVSS 2.04.3MediumNVD

Official description

Microsoft XML Core Services (MSXML) in Windows 10 Gold, 1511, and 1607; Windows 7 SP1; Windows 8.1; Windows RT 8.1; Windows Server 2008 SP2 and R2 SP1; Windows Server 2012 Gold and R2; Windows Server 2016; and Windows Vista SP2 improperly handles objects in memory, allowing attackers to test for files on disk via a crafted web site, aka "Microsoft XML Information Disclosure Vulnerability."

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Restriction of Operations within the Bounds of a Memory Buffer

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.

More Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerabilities (CWE-119)

Timeline

  1. CVE record published.
  2. Added to CISA's Known Exploited Vulnerabilities catalogue.
  3. Deadline for US federal agencies to remediate, set by CISA.
  4. CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: partial).
  5. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Technical write-ups (may include proof of concept)

Other vulnerabilities in XML Core Services

All XML Core Services vulnerabilities

Recent Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerabilities

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