Deutsche Bank recently started forcing its customers to switch their transaction authentication from iTAN to PhotoTAN. Now I wanted to verify the authenticity of the Android app like this:
# jarsigner -verify -verbose:all -certs com.db.pbc.phototan.db-1.apk
s 11870 Mon Oct 02 12:46:02 CEST 2017 META-INF/MANIFEST.MF
X.509, CN=George Georgiades, OU=GT AS Productivity & Collaboration Technologies, O=Deutsche Bank AG, L=London, ST=Unknown, C=UK
[certificate is valid from 10/31/11 12:42 PM to 3/18/39 12:42 PM]
[CertPath not validated: Path does not chain with any of the trust anchors]
11991 Mon Oct 02 12:46:02 CEST 2017 META-INF/DBANDROI.SF
1525 Mon Oct 02 12:46:02 CEST 2017 META-INF/DBANDROI.RSA
sm 3468 Fri Nov 30 01:00:00 CET 1979 AndroidManifest.xml
X.509, CN=George Georgiades, OU=GT AS Productivity & Collaboration Technologies, O=Deutsche Bank AG, L=London, ST=Unknown, C=UK
[certificate is valid from 10/31/11 12:42 PM to 3/18/39 12:42 PM]
[CertPath not validated: Path does not chain with any of the trust anchors]
... and so on, for all files in the APK. So naturally I wonder who this George Georgiades is and why he doesn't have a trust chain:
# unzip -p com.db.pbc.phototan.db-1.apk META-INF/DBANDROI.RSA | openssl pkcs7 -inform DER -noout -print_certs -text
Certificate:
Certificate:
Data:
Version: 3 (0x2)
Serial Number: 705392378 (0x2a0b6efa)
Signature Algorithm: sha256WithRSAEncryption
Issuer: C=UK, ST=Unknown, L=London, O=Deutsche Bank AG, OU=GT AS Productivity & Collaboration Technologies, CN=George Georgiades
Validity
Not Before: Oct 31 11:42:49 2011 GMT
Not After : Mar 18 11:42:49 2039 GMT
Subject: C=UK, ST=Unknown, L=London, O=Deutsche Bank AG, OU=GT AS Productivity & Collaboration Technologies, CN=George Georgiades
Subject Public Key Info:
Public Key Algorithm: rsaEncryption
Public-Key: (2048 bit)
Modulus:
00:99:e5:d6:19:be:44:f7:f6:36:69:00:fd:01:28:
7b:d0:5c:5d:84:52:d2:69:46:1c:d7:23:88:0a:4e:
a8:51:71:2b:29:65:5f:97:92:d6:d8:c0:c2:22:84:
e8:ae:ad:98:55:76:82:36:7e:94:1e:cc:7f:80:c1:
0c:c3:1f:30:b2:f7:35:e9:24:2d:68:b6:a6:15:2c:
12:d4:f3:cc:35:09:3c:fc:7f:b2:8b:3c:eb:98:7a:
52:7a:11:f4:f0:81:55:d0:7c:80:ae:0e:fb:83:4f:
76:32:53:1b:a3:4b:78:20:68:6e:d9:0f:16:46:d4:
40:e7:fb:47:59:8f:9f:95:a4:68:c4:78:d9:37:c5:
e4:5f:16:84:9e:9c:3b:d1:9c:c5:73:c3:35:87:67:
8c:f4:cd:af:eb:70:f1:f9:ac:8c:bd:b2:13:8c:d3:
60:ae:b2:25:e5:41:af:1a:0f:0c:85:dc:87:70:c9:
41:73:e5:77:52:3f:61:ad:bc:99:18:7b:37:5d:a9:
bc:53:1b:7e:4e:52:a4:15:7d:7a:7d:22:fa:2b:f5:
0f:7e:26:70:6d:c4:e6:f6:47:f7:c9:1d:38:01:e0:
36:3d:24:4a:f2:f1:08:33:3a:f6:fc:5e:4b:a3:cf:
a7:ee:fc:54:fc:95:2b:ef:71:6e:36:f3:d5:c4:8b:
9e:1f
Exponent: 65537 (0x10001)
X509v3 extensions:
X509v3 Subject Key Identifier:
5F:11:C3:FC:CD:7C:20:B9:10:4D:04:22:32:37:90:B3:85:EB:A6:DF
Signature Algorithm: sha256WithRSAEncryption
20:21:b3:48:89:14:5d:30:53:3a:7f:72:cf:4b:4c:84:f8:c3:
3b:4d:2c:9f:58:b9:d6:6c:fc:ef:8f:81:c2:4a:07:97:5e:28:
10:3e:b3:6a:4b:9b:38:2b:8e:ca:07:a0:ae:aa:b8:3f:45:11:
b5:84:62:2c:03:67:66:76:9c:d4:2b:b0:5b:15:45:86:9e:01:
41:5c:1c:ea:9c:36:d0:ef:e3:ab:a4:3f:54:ae:2f:e9:b0:63:
5f:c1:a2:e4:5b:d0:5d:66:a8:3c:d4:db:54:38:e1:b2:60:ba:
c9:48:b7:ed:39:e9:fb:47:63:b4:17:ca:d4:2c:56:2f:d5:82:
50:77:b6:46:d5:ca:b6:cf:8f:6a:34:d6:ba:2b:05:c9:04:7b:
65:a8:ea:72:18:2d:f2:fa:e8:7c:1b:92:44:24:dd:e0:e6:47:
9a:88:bc:a4:82:85:d2:8f:45:1c:41:3b:84:08:80:7c:cf:98:
2d:90:06:f9:e1:c9:08:a3:26:6d:64:a2:f7:38:f0:4a:05:b1:
ef:84:d4:e6:df:a4:4e:fc:f0:11:c0:0d:1d:bc:6e:8d:11:22:
09:52:37:bb:52:d8:5e:70:d4:50:02:36:d5:bd:ed:bf:ba:1e:
eb:34:e2:17:ec:9d:6f:4c:7f:4e:9f:b0:e7:4c:2a:17:57:50:
2e:72:83:e1
So now I'm thinking WTF is going on?? Why is the transaction authenticator of Deutsche Bank apparently being developed by some dude in London who uses a self-signed certificate to sign it? Either I'm very confused about how Android app security is supposed to work, or the app is a forgery, or this is just highly unprofessional. Which one is it?
