Stack based buffer overflow

A blog post with additional information is available here:


We have also released a video showing arbitrary code execution:



SEC Consult Vulnerability Lab Security Advisory < 20170511-0 >


title: Stack based buffer overflow

product: Guidance Software EnCase Forensic Imager

vulnerable version: EnCase Forensic Imager <= 7.10

fixed version: -

CVE number: -

impact: critical


found: 2017-02-17

by: W. Ettlinger (Office Vienna)

SEC Consult Vulnerability Lab


An integrated part of SEC Consult

Bangkok - Berlin - Linz - Luxembourg - Montreal - Moscow

Kuala Lumpur - Singapore - Vienna (HQ) - Vilnius - Zurich




Vendor description:


"When time is short and you need to acquire entire volumes or selected

individual folders, EnCase Forensic Imager is your tool of choice. Based on

trusted, industry-standard EnCase Forensic technology, EnCase Forensic Imager:

* Is free to download and use

* Requires no installation

* Is a standalone product that does not require an EnCase Forensic license

* Enables acquisition of local drives (network drives are not able to be

acquired with Imager)

* Provides easy viewing and browsing of potential evidence files, including

folder structures and file metadata

* Can be deployed via USB stick and used to perform acquisition of a live






Business recommendation:


SEC Consult recommends not to use EnCase Forensic Imager for forensic analysis

until a thorough security review has been performed by security professionals

and all identified issues have been resolved.



Vulnerability overview/description:


EnCase Forensic Imager fails to check the length of strings copied from the

definitions of logical volumes in an LVM2 partition. When EnCase Forensic Imager

is used to analyze a crafted LVM2 partition, part of the stack is overwritten

with attacker controlled data. This allows an attacker to overwrite a pointer

to code. After the program execution is transferred to the address specified in

this pointer, the attacker has control of the consequent program execution.


SEC Consult was able utilize this vulnerability to craft a disk image that, when

analyzed, executes arbitrary code. Since EnCase Forensic Imager runs with

administrative privileges, this code runs in an elevated context.


Since EnCase Forensic Imager does not use ASLR or Control Flow Guard, the

probability that an attacker can successfully exploit this vulnerability (and

possibly other vulnerabilities) is significantly higher than in similar software

that utilizes these mechanisms.



Proof of concept:


In order to parse the name of a logical volume from a logical volume definition

EnCase Forensic Imager processes a line that e.g. looks as follows:

testlv {

In order to extract the volume name from this string, EnCase Forensic Imager

first searches for the character '{' within the line and then copies all data

before into another buffer. Since the source buffer is 1024 UTF-16

characters long and the destination buffer is only 258 UTF-16 characters long,

a buffer overflow occurs on the stack.


After a function pointer in the stack frame of the calling method has been

overwritten, this function pointer is being called. Since the method does not

return between overwriting the stack and calling the function pointer, stack

cookies do not protect against this vulnerability.


A demonstration of an exploit has been developed and provided to the vendor.

This exploit creates an LVM2 image that defines a logical volume with a

manipulated name. When the investigator searches for LVM2 logical volumes on

this image the aforementioned pointer on the stack is overwritten. Afterwards,

this pointer is called and execution is transfered to a stack pivot gadget.

Since only strings converted from Windows-1252 to UTF-16 strings can be used in

the overwritten stack memory and since characters below '\a' are transformed,

a series of ROP-chains was required to exploit this vulnerability.

Ultimately the last ROP chain calls VirtualProtect to allow execution of the

attacker-supplied code.


The exploit has been developed to work with the 32-bit version of EnCase

Forensic Imager and will be published at a later date.



Vulnerable / tested versions:


At least version 7.10 of EnCase Forensic Imager has been found to be vulnerable.

This version was the latest at the time the security vulnerabilitiy was




Vendor contact timeline:


2017-02-17: Vulnerability identified, further internal analysis (special thanks

to R. Freingruber for binary exploitation support)

2017-03-07: Sending encrypted advisory to vendor through previous contact via


2017-03-13: Vendor answer: forwarding advisory to engineers, will update us

2017-03-17: Sending Proof of Concept exploit to vendor

2017-03-31: Requesting status update (no response)

2017-04-18: Requesting status update, reminding vendor of upcoming public

release of the advisory (no response)

2017-05-01: Informing vendor (through all available contacts) of the set release

date (2017-05-11)

2017-05-03: Informing four members of executive team about the upcomming


2017-05-03: Guidance Software says they will inform us "if and when further

information is available"

2017-05-09: Informing CERTs (US-CERT, CERT-Bund, about upcoming release

2017-05-11: Public release of the security advisory





The vendor did not provide a fixed version of the affected application.








Advisory URL:






SEC Consult Vulnerability Lab


SEC Consult

Bangkok - Berlin - Linz - Luxembourg - Montreal - Moscow

Kuala Lumpur - Singapore - Vienna (HQ) - Vilnius - Zurich


About SEC Consult Vulnerability Lab

The SEC Consult Vulnerability Lab is an integrated part of SEC Consult. It

ensures the continued knowledge gain of SEC Consult in the field of network

and application security to stay ahead of the attacker. The SEC Consult

Vulnerability Lab supports high-quality penetration testing and the evaluation

of new offensive and defensive technologies for our customers. Hence our

customers obtain the most current information about vulnerabilities and valid

recommendation about the risk profile of new technologies.



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EOF W. Ettlinger @2017