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Date: Sat, 11 Jan 2020 11:23:07 +0100
From: Thierry Zoller <>
Subject: [TZO-06-2020] - Kaspersky Generic Archive Bypass (ZIP FLNMLEN)


                 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 
Vendor          : Kaspersky
Status          : Patched
CVE             : Unknown
Dislosure Policy:
Blog            :
Vendor Advisory :

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 

These types of evasions are now actively being used in offensive 
operations [1]. To my surprise with a few exceptions most AV Vendors 
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 

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 

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 


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

IV. Patch / Advisory
Update to the respective available versions as found at

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

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