黑马python2019吾爱破解_2019KCTF 南充茶坊(python逆向)

1.前言

本文讲的是一道python逆向题，逆向分析python打包程序，首先对它进行解压缩，使用python逆向工具提取出关键py文件，分析py文件中的算法，然后写出求解flag的代码。

2.工具

1.x64dbg

3.pyinstaller

4.3.解题过程

1.选中该软件，右键发现可以解压缩，用binwalk工具发现南充茶馆.exe里面有压缩文件，解压缩后有CM.exe和aplib.dll，用binwalk工具发现CM.exe为打包程序，运行CM.exe文件，发现C:\Users\Lenovo\AppData\Local\Temp\_MEI****目录下有pyd文件，推测其为python打包程序。

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2.用ida打开，看到以下代码，aplib.dll提供解压函数，用编辑工具打开，PE文件在0x8000处，压缩大小为0x28131，x64dbg动态调式，并对aPsafe_depack下断，运行发现解压大小为0x42c00，解压后用插件转存。

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3.打开转存后的文件，把转存后的文件复制粘贴到原文件0x42c00上部,直接用pyinstxtractor发现，识别有问题，接着看文件首和末尾处，发现文件尾部有DEADCODE，而前面是空，删除发现解压成功

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4.提取和反汇编步骤如下：

[Asm] 纯文本查看复制代码C:\Users\lenon\AppData\Local\Programs\Python\Python37\Lib\site-packages\PyInstaller\utils\cliutils>archive_viewer.py CM.exe

pos, length, uncompressed, iscompressed, type, name

[(0, 252, 326, 1, 'm', 'struct'),

(252, 1104, 1807, 1, 'm', 'pyimod01_os_path'),

(1356, 4372, 9350, 1, 'm', 'pyimod02_archive'),

...........................................

'b',

'Crypto\\Random\\OSRNG\\winrandom.cp37-win_amd64.pyd'),

(50657, 6552, 15872, 1, 'b', 'Crypto\\Util\\_counter.cp37-win_amd64.pyd'),

(57209, 48189, 87200, 1, 'b', 'VCRUNTIME140.dll'),

.....................................

(5216615, 1467669, 1467669, 0, 'z', 'PYZ-00.pyz')]

? X CM

to filename? CM.pyc

? O PYZ-00.pyz

Name: (ispkg, pos, len)

{'CMpub': (0, 17, 2250),

'Crypto': (1, 2267, 597),

'Crypto.Cipher': (1, 2864, 1035),

'Crypto.Cipher.AES': (0, 3899, 1596),

'Crypto.Cipher.blockalgo': (0, 5495, 2148),

....................................

? X CMpub

to filename? CMpub.pyc

? X general

to filename? general.pyc

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5.三个文件整合在一起之后的代码如下：

[Python] 纯文本查看复制代码#from CMpub import pub_n_list, pub_e_list

#from general import valid_serial, valid_username, get_enc_seq, enc0

from Crypto.Util.number import bytes_to_long

from os import system

#CMpub.py

pub_n_list = [

1230179032923966355216193664456989083993912178939747632284136330115404600706909248395341278324517175820853286404743710145952644302282044037365125019184623573863075946389644423629304167773956447181872440665027369039751736977631813405,

1230197346433601576871359147146318345794660644587556813317361121112259736906064757424819981626600536503633922734399282271582600808051530362336101942259823441839299355603967188517947938968081105138847731565260537550727639211683197879,

1230175103148238074642625667635930176506433011031372989302833308622794392947506662903737049730958209740476679577696669046125817578949235076594181707520951908118478466754559490593457625240572006099913042624607335165510041897534435209,

1230195419889872144876656964938566328205499234259210834822623032535100815525647028091967713768075507813160118981470260555950945392043292242406398016007295386079663975352275199434079009613722639414793342879897781273997830701207001839,

1230174827420484335136670743465041112031290639257519417607166302989196920558878232997045073571925815302061150702941267642751824310540753494973942944709182841639107639574372312103384805313053886702823094137071927771880443876497834223,

1230185988420782350445684618408731075592594374149632568516959143947765502111474165779039038375448460747737995123102271976521803891348006321134167925739699715318653372703575221067707929872597815216923462345784043188962130180912008349,

1230182067416272799574586563163545941454653137377618375202713428977357995541722463977983142958255155175313052685136009571171283284447072364958073918526788611457558644331357136872625495927467161960356807765452292242153097362794537297,

1230175667673121302771605367336364266247327534138626737357715728447532125946735363769285915448580252805827932111511713836998047583507066247536863749820566853793525683889378074234787827092004094825431802398656705570322640700888234457,

1230196215847264556140155304337951587143228841840811940425256504477922246092127337047231112435502675187836322205816125340569108923142351137471846665258392302281836567949024626839375922984390501852966755563575130612920367863203222919,

1230186684530117755130494958384962720772853569595334792197322452151726400507263657518745202199786469389956474942774063845925192557326303453731548268507917026122142913461670429214311602221240479274737794080665351419597459856902143413]

pub_e_list = [

516522834974778788822737622050071002228140433403308439492366176194856535110473049678585760137133115927927751389873437178270126066640141239601219481836725664034890696476089482771855782560150644578106217444113872365843767702019835165,

763019398230639020385095590111745749325105506404934257293148841704076883985487416392986296273940405033341623636375465706381388882972769884442281412068657916633528090146878551371406807944205178239005601520958614234641039656871416589,

758988267473789691400810521950661631157749425185051374867090671651749645717430551141709267885532654476900928589359256799354189000242807872593092025777838259738748452497031844208902096380110211365512236965688511597330444132995706089,

1160624249765899561934599801255171381291816170997589163041066264243942985094428544791715385847964978883555709070528078257993944356365754193784103706700609561770247555832359683008614876192584738534198649251915489100192910235497240729,

969584864618350548573879514405798110739020997255786147754353418263140741786718203172013471748696400657712445258494301947449205093259143099235572291402265831321039275001497928579686310419303799571460516007736804962510266314260484877,

977635869919691501956476862485989771461480520535754082824505449124021204549179419508424215127475063873127952064971338143136691515421466871627243381628988777601672460858098249144471775030169367579800220246847826510445608881346258241,

78547544255936347746865903259860321812178052069796003154571672431430356709336862994676369608681727972743046653319757142976388460246409300441314120923213061705641045744824531268088986356203751782848608006264879618324460588039470689,

917852167599983949701460374746950168138446186550074700858636881546192542929330983597633909534315139846805451671216776221152853388795036676315895948093016056124384137235869660229554239964598066970045657946753074761366723500887474273,

512767915836808239407587704603826045022417741229198687031456060058182528147222248648359114235863620155721720617193551963387219761946115199232261616095015003006138489919312964841684835736418589367746436759162173805823822810793395319,

1528664914065178933673821962753205462549978186396819666317790993639228285768444490202530533489915241541000489357324333513953018274712260336841857865516134868397620862505815431605074038377372062941322744934135683316080403207986149067]

#general.py

from hashlib import sha256

def valid_serial(serial):

assert type(serial) == str

assert len(serial) > 0

if not '0' != serial[0]:

assert 1 == len(serial)

for c in serial:

if not ord('0') <= ord(c) <= ord('9'):

if not ord('A') <= ord(c) <= ord('F'):

raise AssertionError

return serial

def valid_username(username):

assert type(username) == str

assert len(username) > 0

for c in username:

assert ord(c) > 0

return username

def get_enc_seq(username):

h = sha256()

h.update(username)

hash_value = int(h.hexdigest(), 16)

T = 9

S = 10

stat = [0] * (T + 1)

seq = [0]

n = hash_value

while n > 0:

if S * T > len(seq):

now = n % T + 1

if stat[now] < S:

seq.append(now)

stat[now] += 1

n //= T

return seq

def enc0(m, e, n):

nbit = 192

T = (n.bit_length() - 1) // nbit + 1

ans = 0

for i in range(T - 1, -1, -1):

def xxx(x, t):

return x >> t * nbit & (1 << nbit) - 1

now_n = xxx(n, i)

now_e = xxx(e, i)

now_m = xxx(m, i)

if now_m >= now_n:

return 0

ans = (ans << nbit) + pow(now_m, now_e, now_n)

return ans

#CM.py

def check(serial, seq):

now = serial

for j in range(len(seq)):

i = seq[j]

n = pub_n_list[i]

e = pub_e_list[i]

if now > pub_n_list[i]:

return False

if i > 0:

now = pow(now, e, n)

else:

now = enc0(now, e, n)

if 0 == now:

return False

return now

def main():

username0 = input('Please input Username:\t')

serial0 = input('Please input Serial:\t')

try:

valid_serial(serial0)

valid_username(username0)

except:

print('\nInvalid Input\n')

return

else:

serial = int(serial0, 16)

username = username0.encode('utf-8')

seq = get_enc_seq(username)

username = bytes_to_long(username)

check_value = check(serial, seq)

if check_value == username:

print('\nCorrect!\n')

else:

print('\nOops! The encrypted Serial is not "' + username0 + '".\n')

system('pause')

if __name__ == '__main__':

main()

6.代码分析:首先是验证输入信息，check函数为关键函数，里面有个循环结构，其中i的值的取值范围是：0-9，等价于进行了十次RSA加密，接下来要做的就是求d，求d的算法可参考我发的文章(https://www.52pojie.cn/thread-1070003-1-1.html)。

第一次：

[Asm] 纯文本查看复制代码n = 1230179032923966355216193664456989083993912178939747632284136330115404600706909248395341278324517175820853286404743710145952644302282044037365125019184623573863075946389644423629304167773956447181872440665027369039751736977631813405

把n转换成十六进制为：CAD931A5AEDA20EA5E7956D07284DB74832A28D331ADFEB1FFFFDB4924156BC1CF0E65FBD9840345985858FCC2F58571FFFF43FBA7A3F0E50F38CD120AC5AFB0F6360E79DCF2E935FFFF7B8B04F0DC86ABF13C3F79E202726A2ED42564211F1DL

均分四组：

CAD931A5AEDA20EA5E7956D07284DB74832A28D331ADFEB1

FFFFDB4924156BC1CF0E65FBD9840345985858FCC2F58571

FFFF43FBA7A3F0E50F38CD120AC5AFB0F6360E79DCF2E935

FFFF7B8B04F0DC86ABF13C3F79E202726A2ED42564211F1D

e = 516522834974778788822737622050071002228140433403308439492366176194856535110473049678585760137133115927927751389873437178270126066640141239601219481836725664034890696476089482771855782560150644578106217444113872365843767702019835165

转16进制并均分4组为：

552BD4790ABF307B7ED1C5997D56639E581CBA65B4762769

9A57D7321E5297B133CB0EBA55FC8AB8D7839772C6490FF1

DE5EEA637EE42461497F3B3286B410FDA678C2EB0662F13D

668594EA4C1BA173614B9860AE8BB1231F60A2BFD36B051D

分别求p[i]，q[i]，d[i]，其中p,q可用yafu求解

把求得di拼在一起可得：

d=231349749158583579949039718606348832345605133393805777133420928094319680216601822460127654993430958078940461462422406257359280556871448350189878998731668936956281838863906877563919765029383962761070215049843547656169497792123978897

第二次：

[Asm] 纯文本查看复制代码n为1230197346433601576871359147146318345794660644587556813317361121112259736906064757424819981626600536503633922734399282271582600808051530362336101942259823441839299355603967188517947938968081105138847731565260537550727639211683197879

p = 3012613441

q = 408348887278831461892610983390456945715612189153595698014201723503582993177671598068402822885301113712860820610804438839912419021850712894809826330539771179969086301239790288951959814006579380835620367785931463468740342519

e = 763019398230639020385095590111745749325105506404934257293148841704076883985487416392986296273940405033341623636375465706381388882972769884442281412068657916633528090146878551371406807944205178239005601520958614234641039656871416589

d = 1229061379053482744823152709690434888605435342198642793057361495153090878523561729157374272032362247153476832905266577597936263875922635915871109425948662301015976854125739243408750974498511602088546684816889116185016023460221241669

image.png (122.29 KB, 下载次数: 3)

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接下来的第三次到第十次(除了第五次)都一样，从第三次开始我是使用factordb求解p和q。

第五次

求解第五次的p和q时，迭代几百次会循环，所以不用求d，也许第五次不需要密钥。

7.最后求解的d集合为：

[Asm] 纯文本查看复制代码1229061379053482744823152709690434888605435342198642793057361495153090878523561729157374272032362247153476832905266577597936263875922635915871109425948662301015976854125739243408750974498511602088546684816889116185016023460221241669,

777757116197429014363243483536399809327489478672765799132008796613164652485176625704586327714092043960999487185568710834915265226900792279774759093092549483626423808502139519027474793822444064402879491357824424416255246538629615833,

823517544270505260875748293850542665969704501523967290816451493771583601768953397655610971102989198539746963950912153425409736040224095605717482218948794082459357645210952999432155985335398508720958815348576453854403675948095665769,

201419093613711761798540120588879041236840801068737686325195769604622639638393093247553615834885873886104026065263583851481439063609372020322699902282368593094548575688163522138303256348801329176798576662806247524508598547117027909,

922636550562204599680939922372659456090989853033213781402035071733018496656291847983487357218691366381484789513851952285401356211108779700672241308549478980097499945532484886375918716118514969665502334756552044884230174523807259329,

627567627354326605515830278366021138159090868181225778581524414114680017539982571880336309158282300554534438008003322761037932916796881232969829716072515736525821134512405811777096389132413642826921797756179543381108933388795804769,

87763698610259057934268676955169084425464093902524300758830437447338976666426976224860384022223934601405128988601223084334832120115000652985202766336425151725676233383146800117094745887838499800523801384784235875984207816521259103,

476133969086427941368462698171675198835788633664060460402567958612344234273279077792246479357026462298849835811290909092037603283477920353500979549470973082158764663458247740861805650589884280458476962517272738918503674157481390819]

8.以下是求解序列号的算法

[Python] 纯文本查看复制代码from Crypto.Util.number import bytes_to_long

from hashlib import sha256

d_list = [0,

1229061379053482744823152709690434888605435342198642793057361495153090878523561729157374272032362247153476832905266577597936263875922635915871109425948662301015976854125739243408750974498511602088546684816889116185016023460221241669,

now0_d = [3278088227273880484685188900446423165326324359156241482897,

5595268830569065289149075246423557309146176813871482913465,

5168422726700129702446055556002687483861807983023239862033,

935387432279493795970516178982877288303534264234974679937,

]

now0_n = [6277052177355867862708971469565390229110991711310599757597,

6277031389885428580574088212602983156224270664268963309877,

6277087998938792861042405062580257456598525084583043892593,

4973828634074084070222279013150769733596223651485114564273,

]

pub_n_list = [

pub_e_list = [

def gen_code(name, seq):

now = name

for j in range(len(seq) - 1, -1, -1):

i = seq[j]

n = pub_n_list[i]

d = d_list[i]

e = pub_e_list[i]

if now > pub_n_list[i]:

return False

if i == 5:

for _ in range(972):

now = pow(now, e, n)

elif i > 0:

now = pow(now, d, n)

else:

now = dec0(now, e, n)

return now

def dec0(m, e, n):

nbit = 192

T = (n.bit_length() - 1) // nbit + 1

ans = 0

for i in range(T - 1, -1, -1):

def xxx(x, t):

return x >> t * nbit & (1 << nbit) - 1

now_m = xxx(m, i)

ans = (ans << nbit) + pow(now_m, now0_d[i], now0_n[i])

return ans

def get_enc_seq(username):

h = sha256()

h.update(username)

hash_value = int(h.hexdigest(), 16)

T = 9

S = 10

stat = [0] * (T + 1)

seq = [0]

n = hash_value

while n > 0:

if S * T > len(seq):

now = n % T + 1

if stat[now] < S:

seq.append(now)

stat[now] += 1

n //= T

return seq

def enc0(m, e, n):

nbit = 192

T = (n.bit_length() - 1) // nbit + 1

ans = 0

for i in range(T - 1, -1, -1):

def xxx(x, t):

return x >> t * nbit & (1 << nbit) - 1

now_n = xxx(n, i)

now_e = xxx(e, i)

now_m = xxx(m, i)

if now_m >= now_n:

return 0

ans = (ans << nbit) + pow(now_m, now_e, now_n)

return ans

def check(serial, seq):

now = serial

for j in range(len(seq)):

i = seq[j]

n = pub_n_list[i]

e = pub_e_list[i]

if now > pub_n_list[i]:

return False

if i > 0:

now = pow(now, e, n)

else:

now = enc0(now, e, n)

print 'now,',now

if 0 == now:

return False

return now

def main():

username0 = 'KCTF'

username = username0.encode('utf-8')

seq = get_enc_seq(username)

username = bytes_to_long(username)

serial = gen_code(username, seq)

check_value = check(serial, seq)

if check_value == username:

print 'serial :', hex(serial)[2:].upper()

if __name__ == '__main__':

main()

temp.png (29.25 KB, 下载次数: 3)

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提取码：smjx

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