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Kaspersky Generic Archive Bypass

Kaspersky Generic Archive Bypass
Posted Jan 13, 2020
Authored by Thierry Zoller

The Kaspersky parsing engine supports the ZIP archive format. The parsing engine can be bypassed by specifically manipulating an ZIP Archive (File Name Length Field) so that it can be accessed by an end-user but not the Anti-Virus software. The AV engine is unable to scan the container and gives the file a "clean" rating. A vast array of Kaspersky products are affected.

tags | advisory, virus
MD5 | ea351cdfa434ec38583fdb174905503e

Kaspersky Generic Archive Bypass

Change Mirror Download
________________________________________________________________________

From the low-hanging-fruit-department
Kaspersky Generic Malformed Archive Bypass (ZIP Filename Length)
________________________________________________________________________

Release mode : Coordinated Disclosure / Patched
Ref : [TZO-06-2020] - Kaspersky Generic Archive Bypass (ZIP
FLNMLEN)
Vendor : Kaspersky
Status : Patched
CVE : Unknown
Dislosure Policy: https://caravelahq.com/b/policy/20949
Blog :
https://blog.zoller.lu/p/advisory-tzo-06-2020-kaspersky-generic.html
Vendor Advisory :
https://support.kaspersky.com/general/vulnerability.aspx?el=12430#021219


Introduction
============
10 years ago I took a look at ways to evade AV/DLP Engine detection by
using various techniques and released a metric ton of Advisories. 10 years
later after multiple CISO type roles I wanted to deep dive again and see
how far (or not) the AV industry has reacted to this class of
vulnerabilities.

These types of evasions are now actively being used in offensive
operations [1]. To my surprise with a few exceptions most AV Vendors
haven't,
in some cases I found the very same vulnerabilities that were patched
and disclosed years ago.

Worse than that is the fact that some vendors that were very
collaborative in 2008/2009 have now started to ignore submissions
(until I threaten disclosure)
or are trying to argue that generically evading AV detection is not a
vulnerability.

A lot of exchanges took place on this matter, for instance one vendor
argued that this could not be called a vulnerability because it would
not impact Integrity,
Availability or Confidentiality so it can't possible be a vulnerability.

Even more bothering to me is how the bu bounty platform have created a
distorted Reporter/Vendor relationship and mostly are executed to the
detriment of the customers.
I am collecting my experiences and will write a blog post about this
phenomnon.

There will by many more advisories, hoping that I can finally erradicate
this bug class and I don't have to come back to this 10 years from now
again.

[1]
https://www.bleepingcomputer.com/news/security/specially-crafted-zip-files-used-to-bypass-secure-email-gateways/
https://www.techradar.com/news/zip-files-are-being-used-to-bypass-security-gateways

Affected Products
=================
List of affected products
The issue affected Secure Connection product and consumer products in
those it is incorporated:

Kaspersky Secure Connection prior to version 4.0 (2020) patch E.
Kaspersky Internet Security prior to version 2020 patch E.
Kaspersky Total Security prior to version 2020 patch E.
Kaspersky Security Cloud prior to version 2020 patch E.

Fixed versions
Kaspersky Secure Connection 4.0 (2020) patch E.
Kaspersky Internet Security 2020 patch E.
Kaspersky Total Security 2020 patch E.
Kaspersky Security Cloud 2020 patch E.


I. Background
----------------------------
Kaspersky Lab is a multinational cybersecurity and anti-virus provider
headquartered in Moscow, Russia and operated by a holding company in the
United Kingdom. It was founded in 1997 . Kaspersky Lab develops and
sells antivirus, internet security, password management, endpoint
security, and other cybersecurity
products and services.


II. Description
----------------------------
The parsing engine supports the ZIP archive format. The parsing engine
can be bypassed by specifically manipulating an ZIP Archive (File Name
lenght Field) so that it can be accessed by an end-user but not the
Anti-Virus software. The AV engine is unable to scan the container and
gives the file a "clean" rating.

I may release further details after all known vulnerable vendors have
patched their engines.


III. Impact
----------------------------
Impacts depends on the contextual use of the product and engine within
the organisation of a customer. Gateway Products (Email, HTTP Proxy etc)
may allow the file through unscanned and give it a clean bill of health.
Server side AV software will not be able to discover any code or sample
contained within this ISO file and it will not raise suspicion even if
you know exactly what you are looking for (Which is for example great to
hide your implants or Exfiltration/Pivot Server).

There is a lot more to be said about this bug class, so rather than bore
you with it in
this advisory I provide a link to my 2009 blog post
http://blog.zoller.lu/2009/04/case-for-av-bypassesevasions.html

IV. Patch / Advisory
----------------------------
Update to the respective available versions as found at
https://support.kaspersky.com/general/vulnerability.aspx?el=12430#021219


Thanks go out to Kaspersky for their cooperation in responsibly patching
and disclosing this vulnerability.

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