5,406 users solved

Description

Can you figure out what is in the eax register? Put your answer in the picoCTF flag format: picoCTF{n} where n is the contents of the eax register in the decimal number base. If the answer was 0x11 your flag would be picoCTF{17}.Download the assembly dump here.

Hints

Not everything in this disassembly listing is optimal.

---

01. 解题过程

好简单的汇编。。。eax的变化写在注释里了

<+0>:     endbr64

<+4>:     push   rbp

<+5>:     mov    rbp,rsp

<+8>:     mov    DWORD PTR [rbp-0x14],edi

<+11>:    mov    QWORD PTR [rbp-0x20],rsi

<+15>:    mov    DWORD PTR [rbp-0xc],0x9fe1a

<+22>:    mov    DWORD PTR [rbp-0x8],0x4

<+29>:    mov    eax,DWORD PTR [rbp-0xc] ;0x9fe1a

<+32>:    imul   eax,DWORD PTR [rbp-0x8] ;0x27F868

<+36>:    add    eax,0x1f5               ;0x27FA5D

<+41>:    mov    DWORD PTR [rbp-0x4],eax

<+44>:    mov    eax,DWORD PTR [rbp-0x4]

<+47>:    pop    rbp

<+48>:    ret

flag

picoCTF{2619997}