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Hardening The Attack Surface
presented by
Hardening The Attack Surface
UEFI Winter Plugfest – February 21-23, 2012 Presented by
Douglas MacIver Principal Test Engineer, Microsoft Corp.
UEFI Plugfest – February 2012 www.uefi.org 1
Updated 2011-06-01
Hardening The Attack Surface UEFI Plugfest – February 2012 www.uefi.org 2
Hardening The Attack Surface UEFI Plugfest – February 2012 www.uefi.org 3
Harden
Attack
Surface
Hardening The Attack Surface
How to Harden an Attack Surface
• Threat Modeling
• Secure Coding
• Security Code Audits
• Fuzz Testing
• Software Security Defenses
UEFI Plugfest – February 2012 www.uefi.org 4
Hardening The Attack Surface
Media Player Threat Model
UEFI Plugfest – February 2012 www.uefi.org 5
Hardening The Attack Surface
UEFI Threat Model
UEFI Plugfest – February 2012 www.uefi.org 6
Hardening The Attack Surface
Secure Coding (one aspect)
Validation of untrusted input!
Poor validation of untrusted input may result in:
– Buffer overflows
– Integer and pointer corruption
– Memory overwrites
– …
Leading to:
– Compromised runtime integrity of authenticated components
– …
UEFI Plugfest – February
2012 www.uefi.org 7
Hardening The Attack Surface
Security Code Audits
UINT32 FindJamInBlob(BLOB* Blob, size_t BlobSize)
{
UINT32 JamOffset;
JamOffset = Blob->Start + Blob->Hdr.Size;
return JamOffset;
}
First, ask questions
Second, identify vulnerabilities
UEFI Plugfest – February
2012 www.uefi.org 8
Hardening The Attack Surface
Venn and the Art of Security Testing
UEFI Plugfest – February 2012 www.uefi.org 9
design implementation
customer wants/needs
bad design
bad impl
? bad design
bad impl
lucky
sadness
bad design
good impl
good design
bad impl
Hardening The Attack Surface
Fuzz Testing
UEFI Plugfest – February
2012 www.uefi.org 10
Format Aware
Fix-up Instrumented
Feedback Informed
Dumb
Effo
rt
Applying malformed data against the attack surface
Hardening The Attack Surface
Software Security Defenses
• Writing Secure Code
• Stack Buffer Overrun Detection (GS)
• Data Execution Prevention (DEP/NX)
• Address Space Layout Randomization (ASLR)
• Heap Corruption Detection
• Migration to Safer Functions
Hardening The Attack Surface
How to Harden and Attack Surface
UEFI Plugfest – February 2012 www.uefi.org 12
• Secure Coding: helps to avoid problems Guidelines for Writing Secure Code: http://msdn.microsoft.com/en-us/library/ms182020.aspx Writing Secure Code: http://msdn.microsoft.com/en-us/security/aa570401 Safe Integer Arithmetic in C: http://blogs.msdn.com/b/michael_howard/archive/2006/02/02/523392.aspx
• Threat Modeling: helps to define trust boundaries and potentially malicious data input points http://www.microsoft.com/security/sdl/adopt/threatmodeling.aspx
• Security Code Audits: helps identify vulnerabilities through manual code inspection http://technet.microsoft.com/en-us/library/cc723542.aspx http://blogs.msdn.com/b/sdl/archive/2011/10/19/code-analysis-for-all.aspx
• Fuzz Testing: helps find input parsing and other vulnerabilities http://msdn.microsoft.com/en-us/testing/cc162782.aspx
• Software Security Defenses: helps provide blanket protection against some threats http://msdn.microsoft.com/en-us/library/bb430720.aspx
Hardening The Attack Surface UEFI Plugfest – February 2012 www.uefi.org 13
Harden
Attack
Surface
Hardening The Attack Surface
Thanks for attending the UEFI Winter Plugfest 2012
For more information on the Unified EFI Forum and UEFI Specifications, visit http://www.uefi.org
presented by
UEFI Plugfest – February 2012 www.uefi.org 14
