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Security
Malware Analysis
Opinion about behavioral analysis
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<blockquote data-quote="tim one" data-source="post: 666943" data-attributes="member: 25920"><p>Yes, to see if a process is under a debugger using IsDebuggerPresent is a common method.</p><p></p><p>For example:</p><p></p><p>[CODE]function IsDebuggerPresent:boolean; external 'kernel32.dll' ;</p><p></p><p>procedure CheckDebugger;</p><p>begin</p><p>if IsDebuggerPresent then</p><p>MessageBox('ok');</p><p>else</p><p>MessageBox('no');</p><p>end; [/CODE]</p><p></p><p>This function does exactly the same thing i.e. to check the third byte of the PEB, only that it uses a little different method:</p><p></p><p>[CODE]64:A1 1800000 MOV EAX,DWORD PTR FS:[18] //get the address of the TEB itself</p><p>8B40 30 MOV EAX,DWORD PTR DS:[EAX+30]//get the address of PEB</p><p>0FB640 02 MOVZX EAX,BYTE PTR DS:[EAX+2]//Gets the third byte and uses it as a response[/CODE]</p><p></p><p>If the byte is 1 then the answer will be positive; otherwise it is not.</p></blockquote><p></p>
[QUOTE="tim one, post: 666943, member: 25920"] Yes, to see if a process is under a debugger using IsDebuggerPresent is a common method. For example: [CODE]function IsDebuggerPresent:boolean; external 'kernel32.dll' ; procedure CheckDebugger; begin if IsDebuggerPresent then MessageBox('ok'); else MessageBox('no'); end; [/CODE] This function does exactly the same thing i.e. to check the third byte of the PEB, only that it uses a little different method: [CODE]64:A1 1800000 MOV EAX,DWORD PTR FS:[18] //get the address of the TEB itself 8B40 30 MOV EAX,DWORD PTR DS:[EAX+30]//get the address of PEB 0FB640 02 MOVZX EAX,BYTE PTR DS:[EAX+2]//Gets the third byte and uses it as a response[/CODE] If the byte is 1 then the answer will be positive; otherwise it is not. [/QUOTE]
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