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1 | /* | |
2 | Four YARA rules to check for payloads on systems. Thanks to sinkholing, encyrption may not occur, BUT you may still have binaries lying around. | |
3 | If you get a match for "WannaDecryptor" and not for Wanna_Sample, then you may have a variant! | |
4 | ||
5 | Check out http://yara.readthedocs.io on how to write and add a rule as below and index your | |
6 | rule by the sample hashes. Add, share, rinse and repeat! | |
7 | */ | |
8 | ||
9 | rule WannaDecryptor: WannaDecryptor | |
10 | { | |
11 | meta: | |
12 | description = "Detection for common strings of WannaDecryptor" | |
13 | ||
14 | strings: | |
15 | $id1 = "taskdl.exe" | |
16 | $id2 = "taskse.exe" | |
17 | $id3 = "r.wnry" | |
18 | $id4 = "s.wnry" | |
19 | $id5 = "t.wnry" | |
20 | $id6 = "u.wnry" | |
21 | $id7 = "msg/m_" | |
22 | ||
23 | condition: | |
24 | 3 of them | |
25 | } | |
26 | rule Wanna_Sample_84c82835a5d21bbcf75a61706d8ab549: Wanna_Sample_84c82835a5d21bbcf75a61706d8ab549 | |
27 | { | |
28 | meta: | |
29 | description = "Specific sample match for WannaCryptor" | |
30 | MD5 = "84c82835a5d21bbcf75a61706d8ab549" | |
31 | SHA1 = "5ff465afaabcbf0150d1a3ab2c2e74f3a4426467" | |
32 | SHA256 = "ed01ebfbc9eb5bbea545af4d01bf5f1071661840480439c6e5babe8e080e41aa" | |
33 | INFO = "Looks for 'taskdl' and 'taskse' at known offsets" | |
34 | ||
35 | strings: | |
36 | $taskdl = { 00 74 61 73 6b 64 6c } | |
37 | $taskse = { 00 74 61 73 6b 73 65 } | |
38 | ||
39 | condition: | |
40 | $taskdl at 3419456 and $taskse at 3422953 | |
41 | } | |
42 | rule Wanna_Sample_4da1f312a214c07143abeeafb695d904: Wanna_Sample_4da1f312a214c07143abeeafb695d904 | |
43 | { | |
44 | meta: | |
45 | description = "Specific sample match for WannaCryptor" | |
46 | MD5 = "4da1f312a214c07143abeeafb695d904" | |
47 | SHA1 = "b629f072c9241fd2451f1cbca2290197e72a8f5e" | |
48 | SHA256 = "aee20f9188a5c3954623583c6b0e6623ec90d5cd3fdec4e1001646e27664002c" | |
49 | INFO = "Looks for offsets of r.wry and s.wry instances" | |
50 | ||
51 | strings: | |
52 | $rwnry = { 72 2e 77 72 79 } | |
53 | $swnry = { 73 2e 77 72 79 } | |
54 | ||
55 | condition: | |
56 | $rwnry at 88195 and $swnry at 88656 and $rwnry at 4495639 | |
57 | } | |
58 | rule NHS_Strain_Wanna: NHS_Strain_Wanna | |
59 | { | |
60 | meta: | |
61 | description = "Detection for worm-strain bundle of Wcry, DOublePulsar" | |
62 | MD5 = "db349b97c37d22f5ea1d1841e3c89eb4" | |
63 | SHA1 = "e889544aff85ffaf8b0d0da705105dee7c97fe26" | |
64 | SHA256 = "24d004a104d4d54034dbcffc2a4b19a11f39008a575aa614ea04703480b1022c" | |
65 | INFO = "Looks for specific offsets of c.wnry and t.wnry strings" | |
66 | ||
67 | strings: | |
68 | $cwnry = { 63 2e 77 6e 72 79 } | |
69 | $twnry = { 74 2e 77 6e 72 79 } | |
70 | ||
71 | condition: | |
72 | $cwnry at 262324 and $twnry at 267672 and $cwnry at 284970 | |
73 | } |