Created
January 17, 2023 03:03
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a python script that decrypts foscam firmware encryption given args found in FirmwareUpgrade (see post for more details: https://hacked.codes/2023/extracting-firmware-reverse-engineering-encryption-keys-foscam/
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""" | |
Psuedo C code from Ghidra: | |
ReformString(char*, char const*, unsigned int, ...) | |
char * ReformString(char *param_1,char *param_2,uint param_3,...) { | |
char *pcVar1; | |
int in_r3; | |
uint uVar2; | |
int local_4; | |
local_4 = in_r3; | |
pcVar1 = param_1; | |
if ((param_1 != (char *)0x0) && (pcVar1 = param_2, param_2 != (char *)0x0)) { | |
for (uVar2 = 0; uVar2 != param_3; uVar2 = uVar2 + 1) { | |
param_1[uVar2] = param_2[(&local_4)[uVar2]]; | |
} | |
param_1[uVar2] = '\0'; | |
pcVar1 = param_1; | |
} | |
return pcVar1; | |
} | |
""" | |
def ReformString(charset, length, *args): | |
buff = [0] * (length + 1) | |
if charset != None: | |
for n in range(length): | |
buff[n] = charset[args[n]] | |
buff[n + 1] = '\0' | |
return ''.join(str(x) for x in buff) | |
charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789~!@#$%^&*()_+|`-={}[]:;'<>?,./\" \\" | |
length = 0x3c | |
result = ReformString( | |
charset, | |
length, | |
0xe,0xf,4,0xd,0x12,0x12,0xb,0x5d,4,0xd,2,0x5d,0x4d,3,0x5d,0x4d,0,4,0x12,0x4d, | |
0x35,0x36,0x3c,0x4d,2,1,2,0x5d,0x4d,0xc,3,0x5d,0xc,3,0x39,0x5d,0x4d,10,0x5d,0x30,0x30, | |
0x33,0x3b,0x19,0x18,0x46,0x15,0x36,0x5d,0x4d,8,0xd,0x5d,0x43,0x12,0x5d,0x57,0x5d, | |
0x43,0x12 | |
) | |
print(result) | |
# openssl enc -d -aes-128-cbc -md md5 -k WWZ7zy*v2 -in %s > %s |
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