Locky: New Ransomware Mimics Dridex-Style Distribution

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Category: Ransomware, Threat Prevention, Unit 42

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Ransomware persists as one of the top crimeware threats thus far into 2016. While the use of document-based macros for ransomware distribution remains relatively uncommon, a new family calling itself "Locky" has borrowed the technique from the eminently successful Dridex to maximize its target base. We first learned of Locky through Invincea and expanded on qualifying this threat with the help of PhishMe. Locky has also gained enough traction to find its way onto Dynamoo’s Blog and Reddit.

Using Palo Alto Networks AutoFocus, Unit 42 observed over 400,000 individual sessions containing the Bartallex macro downloader, which in turned dropped Locky ransomware onto victim machines. Researchers suspect there is a link between the Dridex botnet affiliate 220 and Locky due to similar styles of distribution, overlapping filenames, and an absence of campaigns from this particularly aggressive affiliate coinciding with the initial emergence of Locky. This blog post explores this threat further and offers recommendations on mitigating its impact.

Delivery and Installation

Palo Alto Networks telemetry showed that Locky focuses primarily on e-mail delivery through massive phishing campaigns with Microsoft Word document attachments. The subjects for these malicious messages adhere to the following convention:

ATTN: Invoice_J-< 8-digits>

The naming convention of respective malicious Word document carrier files match the e-mail subject line portion after the “ATTN: “, switch the “i” in invoice to lowercase, and append a “.doc” extension. An example follows:

Subject: ATTN: Invoice J-11256978
Attachment: invoice_J-11256978.doc

Our analysis revealed that this ransomware requires command and control (C2) communication for a key exchange, prior to encrypting victim files. It performs its key exchange in memory for this process. This is interesting, as most ransomware generates a random encryption key locally on the victim host and then transmits an encrypted copy to attacker infrastructure. This also presents an actionable strategy for mitigating this generation of Locky by disrupting associated C2.

Unfortunate victims unable to mitigate this threat would see the following ransom demand.

locky1

And a subsequent visit to the referenced Locky payment portal site would reveal the following options for victims.

locky2

Threat Volume and Targeting

We observed approximately 446,000 sessions for this threat, over half of which targeted the United States (54%). For comparison, the next most impacted countries, Canada and Australia, only accounted for another nine percent combined.

locky3

Industry analysis for targeting reveals expected indiscriminant distribution within impacted countries; however, Higher Education, Wholesale and Retail, and Manufacturing make up over a third of observed targeting.

Pairing this volume with the “decryption cost” advertised for Locky victims, it is clear why ransomware in general continues to thrive in the threat landscape. Using some napkin math furnished by our friends at PhishMe, even if one assumed a 50% efficacy / infection rate for these 446,000 sessions and a 1% payment rate of 0.5 bitcoins (BTC) from victims, the currently observed activity alone yields several hundred thousands of dollars in profits for Locky’s malicious actors.

Conclusion

Locky is aiming high in an effort to join the ranks of other big name ransomware families. Despite some weaknesses in its current implementation, we can expect to see further developments for this threat in the future. Ultimately, successes experienced by one attacker group embolden and inspire others. It goes without saying that cybercrime adversaries will continue to advance efforts to commoditize the already lucrative extortion of victims through encryption-based extortion.

Defending against ransomware first requires a focus on the basics of a strong security posture: security awareness and the hardening and patching of systems. Ransomware can be especially damaging in enterprises, where this class of threat commonly targets network shares and other media attached to corporate assets. To further reduce associated risks, layered preventive controls are a must.

Palo Alto Networks customers are protected through our next-generation security platform:

  • WildFire successfully detects this threat as malware
  • AutoFocus identifies this threat under the Unit 42 “Locky” tag
  • The C2 domains and files mentioned in this report are blocked in our Threat Prevention product

Indicators of Compromise (IOCs)

Type Indicator
E-mail Subject ATTN: Invoice_J-<8-digits>
Attachment Filename invoice_J-<8-digits>.doc
C2 109.234.38.35
C2 173.214.183.81
C2 193.124.181.169
C2 195.154.241.208
C2 195.64.154.14
C2 46.4.239.76
C2 66.133.129.5
C2 86.104.134.144
C2 91.195.12.185
C2 iynus.net
C2 www.iglobali.com
C2 www.jesusdenazaret.com.ve
C2 www.southlife.church
C2 www.villaggio.airwave.at
SHA256 ee6abe4a9530b78e997d9c28394356216778eaf2d46aa3503999e7d6bfbefe90
SHA256 5466fb6309bfe0bbbb109af3ccfa0c67305c3464b0fdffcec6eda7fcb774757e
SHA256 add7794c4d70fd49c96c11dc924c6b65c4459d6295331414b40768867dab0350
SHA256 e7277e4aa4905168f6890c6b7b80515030806db46b7ec41a8afa33d6dda231dc
SHA256 6e2a597d8c6b4ebc6474c4a96bce61340a1a66b7e8e33cdf42f3e34cef1a94fe
SHA256 76bcba80045b043e8e69f7a2a92bc8879e7b13e29d50f10b41c11bd114a288ae
SHA256 e37cb6cb2d39e3ceeb946e4a55890cd278a0ba3d541c0d18a22a0bf84c1dcadb
SHA256 18f7150992020e369dbc2aa32fdec2e3003d782716a79be654b9e4eecff0113a
SHA256 c9bfb22f9655e53dacbce66c4bfba1e5b42250f0b41973c1e4433f285ed73d79
SHA256 41a7bfe77c89b3c151f0e847e44e8f58d63ed82a8ad370bc679c29d89a20a657
SHA256 1833ea2138d21962d6f47def5d01cbec299eb6deb89fe729fd5b80c0f603a766
SHA256 03da53e5fe550a1914179d5102479771651d4fa8797f46df3e4f66a05fa64bd6
SHA256 338f15ac0d07db13e1f291c53aa004f46d994ee5bacd2787c0d536284b465f9e
SHA256 1d8cc4e8416b5ac16864583e8bb0d8f8d8ad4b32de7de111067c38da0cfc57b1
SHA256 abdbc74907d7670a65b5a4cc8c08da751cc837a11d1abb43e3ddaa932bdbf60c
SHA256 8877b9a036b76495d9f4add16d56c8819d12a92cd32ae0e4c06be4faa719a991
SHA256 4ae1f9229bfb5385949a4dfe0ac89a49d785646389be556f90ad5d29e5ecc35f
SHA256 b10733a1aa02d973d00bd780c7f1a7d1e71fd50155f2cfecfb2a8f1662aa1cd5
SHA256 8a248e85579cde3e0e8e20f254ec2c15ce063f580084be2dca1f8e725ae7f148
SHA256 11206eb0cfa0df32ef0b4d2cd2a704be11cbd6e6bc6a2d83eaf0ddf977d76ac5
SHA256 521d2885aec43104e3903988f23e42a2543682556afc51bff44bb939c74eb421
SHA256 3d84dd3f392eadaf3916c3f71cf98606c25f48feaad60b74af7196171aade0a7
SHA256 17c3d74e3c0645edb4b5145335b342d2929c92dff856cca1a5e79fa5d935fec2
SHA256 329197ec2fffb6365adee8b7302912c8ef0f7550f63c92887d2cfae432a15df4
SHA256 f81d543f5144fe8dc1d0bb84625ed298867d9b34f805c7d26ce26f37d325467a
SHA256 5843c22f9e27cd8a217114b21ccc706dafe40f626dc9fcef0000a7f79b2aad66
SHA256 d0df113d589fe481bc045bda948ace1f2b9c43b4bd0652f00b0fbb096a2fb39c
SHA256 a6189f9796f1c782b95eb6e0bc030e8d1de924efdafff8e329876b09b2b5173f
SHA256 f3712d591fbf403d23eed006d5c5bb5b94e13360920a04095968d1a914bc3ff8
SHA256 348c92b47a27fbf427d1093f09ef662dbd11846ca1f3e8cf9ba2dda8008f9c4f
SHA256 1083fd1d0a02d36582b78fdba4478e75401f7ec37359f6d8142426f8f3523328
SHA256 2e1305b440274e1f4340a10180709b83f5aad182963d6f6594613e71b309d7d5
SHA256 e6079af75b4a06f6ce95cb95d3de3b8af89afbf7722a64a6f7b04f3c643024b2
SHA256 dca90037836376ce5634f277ee21e779462b6faaff83ade1ba36f75fc0bc255b
SHA256 5fc15b920f00f427350987ae192b9baf2eb0fecfc662985fb612e8ebc60f9b30
SHA256 0c38c96617436fadf66852e48365def3e00b297c7f160617768bebd09f15658d
SHA256 13bd70822009e07f1d0549e96b8a4aec0ade07bea2c28d42d782bacc11259cf5
SHA256 9b5653a986529c2eebc429387f3dea52ea167ccb259b6f57491d14ea4b86627e
SHA256 55645af2a4c54c6c1141b7261ca598d2e250a5a1b51731920cf7c09264c4c160
SHA256 1c5c1c287cd6151da44571b8cfae526b0b6e6d09faaa6723fdd040cb595b9fd0
SHA256 89b732003c08f0f1c2f8a0412b1c2f0efc216ae0204103326571e1831e28b09e
SHA256 711147bfafee1b3f71b0c8e9d00bb139401c207ca5518e2c02a6b0a7367cc9c2
SHA256 53e91bbc1de973265ef3366201a70bce385951f805d2d9ebc9ab5f2d7627b7d3
SHA256 f56655bfbd1be9eab245dc283b7c71991881a845f3caf8fb930f7baabae51059
SHA256 555fb717902e671c26848ee80788769a1c88ac00c9f8440250f9936632597bc8
SHA256 a5b2d0f5367bebd70137e0ebf3286d80434789e95aca488ffd8391905dd98fd9
SHA256 da21dbe14f408ddb3de2e57fb77fd94e8615cb6cce5b7c541b8fe4e309b7fb6c
SHA256 fd5c0d976292b233328ea085f101bbef9c6cae2007d275a5e6e07149d86c7968
SHA256 7c3651cb149cb5f9a4db6b64e412fcd23977f5c083bdfd3ee8c7bbf929e20b4d
SHA256 7b39dfb32220e3f653ce8ec124a3f1541230c158533ea4b799e766bb1f77b96f
SHA256 e77aec1984755d69692487acbf1ce4743726714ffe9168610a49e05723e891cd
SHA256 0661bd8cefcc41bba4322077b6ab96d49054074c6aa2a917acf87ff815d53e49
SHA256 5bae6d580e1e16d29233f7164ce6aadfabcbd562b9137e92997e4ad3854926fd
SHA256 ec9ac36b8ef41ecda870ed41297592a34e3250db821c8d518701c0e486c9379f
SHA256 1c8ebb27ad656d720c854a476d6f0e1de4288e9f2a4c60ae35bb7020dedf5239
SHA256 db3bc157f8f6bda96c63d2ba40c74e7bfd4d451d87eaa8ed02ce9ee692098d15
SHA256 9cc592720e4d859f7cd2995587e1f724133ff3008164261ea7fb7e3269ac597a
SHA256 c866dcfa95c50443ed5e0b4d2c0b63c1443ad330cb7d384370a244c6f58ce8a5
SHA256 2dbfd8f5e20168a52dadf694fc9e63c8f09356dae60fd79e00897dc094a48cb6
SHA256 78e9558a9762cf778a3ba9ba61e0ec73e8d81c22d0945e56ea75d197c512883a
SHA256 708bae89b1866c85243f02b011d4d1e9585305845bf7a4df4430927cd5af8c27
SHA256 7c9c451a3a3bded9aad02297f611e425b3649e629e4c5e24a7ccb7928babb006
SHA256 069464563ca340ef167b29b55797bbb63792c00700a867437fdd9f640e99aa09
SHA256 cba9de885f30b627d9c30079a22956e61cd1b03d10ec972ef9c90f8d23cff8aa
SHA256 1f126aabbf32507f4385fe335b46fbb46234b2c25909ed6884ed664a5c93d0f9
SHA256 1bad53ce984f652bc03ecb96fad5746357968c2fdccdea82995231f1099773e4
SHA256 62a19c7a08db69a45ecf009955e6d8aa441079dea06770af1a953b681a0d81a2
SHA256 1450fa0c4f5973ebf3efa06fb03259105065baba29690362014926583bc85f48
SHA256 d6772478ab901d81514b0d04852380932ee214b364dff246c3f91963d9ec6927
SHA256 ec9bfe9c9d44437c04209269fcd26815dc99416722bb4f4a4a2049bc41c63cc6
SHA256 acf01ba44f916a8f82f76c0b91021fd79d4968e3aa312fb77904a9757058b5ac
SHA256 d69b7f196fa8a2298e261333d4794ac34a8a4503c26750c3d5a012b2b7b327f5
SHA256 134ef8198282652fb98e4174deda4d105db53c54d50039a2c0f6eb283eed8a1b
SHA256 50c2b1f4b32fcd43fa9871f51f72d2b227eab1a3e5d04159d326a22e56305dc8
SHA256 e5aecadf8f132b64384bba0f1ffbf317637eed11398a0d6ef789b1dc10db4cb1
SHA256 87068696c0291fe976f62afb23ff2720d53dfd638a6953c0d0867d9ad4ea451a
SHA256 c7ab7c65e65cdc13bbb991403c1338c556500472114ba79bb31356eecabd0089
SHA256 eaa4d072b1eb53b2dae7d5396e67c03e523fe05f76f793c991119463b1f8522c
SHA256 3eb1e97e1bd96b919170c0439307a326aa28acc84b1f644e81e17d24794b9b57
SHA256 2059727c6447781b2dc2e4c51c126bc0b7f05b9c23b3edf365332d90c078b7f6
SHA256 d9de8ff8c82baeeab0e1e355f9f5025547ba40cb8d95e9cad9dc25ffdb690057
SHA256 915be79a2330c1fcb9e0cf392913986dbe9bf7a404cdf88a65ae148586b162d5
SHA256 5549b000fd38a2634adbe956d46f7bb649eda8efd768ef8919a703378885186b
SHA256 bc98c8b22461a2c2631b2feec399208fdc4ecd1cd2229066c2f385caa958daa3
SHA256 83279bbeb581892ccee9cfa7d37b73674d55380d55d78123781b3c38a2d8ffe0
SHA256 f519f99c9b49cf730cb092d83350002fb0d90fd705c86ed306c36f38fd6af10a
SHA256 50a2235f356d59269b98f1d6420afa257651b33e9d9af5af56ab777c331dc6dd
SHA256 d7d23b516041299868eb67a814e22064a05f06283a673a186e24d184521fa33e
SHA256 8545aa956982bf6f5763058cbde3f8c92e1dcbfb699a7248969ef12bb59a615c
SHA256 3d08eb860a2a13e7fc36f7750a4a87cf11b994a19343234b8e0621fa951e5a38
SHA256 488947790c6aba7dff05c5f1c9ce1d24b3f9e5a0677f1695bbd6ae2bd9d48236
SHA256 d2369ae9977cbb23cfe1c63f6deb0d7fabe9ee38980831c8a636f91342f716c1
SHA256 b16ed0060bd5359fc695b965ce4c459bbe73e083094aff720837739487fd2900
SHA256 3c305696f35fe10eb27a97bb76bc737654727b33e81333c8fe73aeded98b6ca8
SHA256 cf836b6a36bffc5a4545a27cc66bc9ddfd49483500aa1f055671e40f06e34221
SHA256 66bf8957d55e0aacc3c2472ebd8966dc3370503e59d57f27ddbc1a83bcf5102a
SHA256 2114322ecc57f0fab5dd1e5b348a066fcfd7baf8ced89fcdb23df172e30a4189
SHA256 971b389bd82806942c44b48bdd0a4ac560377b7fcb5c872264796705b769414a
SHA256 8426bdde88e8e59c56ab4ff6b32dfd1080dfc0fc86980a853802e9aea1773c47
SHA256 fa3f2cf4b2f1a0393383294dae8ba20709b1ce0985b6fe8e51ccd90cb609ca6e
SHA256 20c37d343ba95aed4180d75825a06828783e924f81a1237c4a68252e0ce97f2d
SHA256 46cf36241696d4127b5d32cbde63a672d9a037d9d47bd59ae8346d83424b53c9
SHA256 892fe60e489e229eb46627241b6078a5b213a4d1840bd39cc939f90cf903a560
SHA256 4d203ae53a96b8207c81ecc0167bb06db3e67bb365639972b9ef22dafbbc189a
SHA256 a32f9eff7fca4f8b98b553b90915b28d4e11e523d36bb64b41f1793c2ed7cf94
SHA256 7f540e391b55221f7696031471b6f8d2068677a67ed8782d52a67872096d23a2
SHA256 408f10baec56c62cc4692d1ba98aa77e7847a7b6f1d3cf812dd2f51c93d580a3
SHA256 2410b7f81082b216c5edd99b4b0a22e7709b0e05b0f6961d4f93ee1a05590237
SHA256 566878276748089f6e87b20fd18bfab4018d9e33fae6e28cb87ffb43b1b80582
SHA256 0a6f1b58819fe0d5f0595be96847f9cb9722777501771d3066d1e7fd39fa3d48
SHA256 d9d3acec0620a1395dda087318de075573fa3b4352641aedc01a16a921c11b5d
SHA256 6e10b784d653ceca19a234411df7a570cb0923bef9a3fe1d91da1e8eb10306d3
SHA256 8988323e0c8b26a3cb0166104001c8d5fd818bef72b506bd03403a2c7c552e8d
SHA256 e7d7b7c8b9cba4dcfee5648f25ad0380c86398cd0b6cba59c3ee8256425d19e6
SHA256 057c1fc879ff7fed218ef3142a0f8761b2651a4c060dc7d853e5621cddc0e6f9
SHA256 ca7ea4325e6e55c504d29f0b080a5755aef771772d8c51f5016e4ce6ed88ccd0
SHA256 77ea0b407dece7f22b0b4732ec06fb0e887262d847a49b9f8cd8611a5c865af4
SHA256 5ad06eda999a9f2f28c2057ba40bd2f7b6a7cb2e1915104b2724753649e97de5
SHA256 584a2767e5881c7f91a04ca2cd78e62e9d52841eea5e0ca7fcd197553666a827
SHA256 a756d84edecae5f17726ba1e59cbc3a622f84159e293a875c24bacf1038f69f1
SHA256 6d76567220652b0d03b34feafaef8b32a472bfd9d617b6eff4db5254c959bf6e
SHA256 1227d8b7e375dfaf0ff76053e3ab158c0635cb288dc1a2f083536f5fe1820ddd
SHA256 8d6be9b4df6679cc5db1750500e3e1645f885878223936670e9ce0442cd0e999
SHA256 82761eb506711dd35af4fe7b71a4e926e1bd70d4dacadd1bb3e68bcd3ef480f3
SHA256 9524daf160f35c3217df680f5676c8f177bc9a3de5b6a128d52bc46d97df96c0
SHA256 c9303f7405c88da80d94df5b11c514ce791becab02e06dfbf4796f361fb93108
SHA256 815530458a2e17fd67774a6802c49423088ddde0ae23e179cc4a608e088c276a
SHA256 66314449bc3bd2772ff062c05ba21f1aa408ce4f7ff73ad37f0f7a2388ab819e
SHA256 4b08d86ca080234c2432613e6730d06dd8c703b35ea7effc999a0e3c3b11ec48
SHA256 88718a0ff51b2e7d9e17d8796cfed1f52d78653c42e3c5dd597833ee0036d803
SHA256 feba92e398ba6da41cccffb0e6b5aacdee27fcfa4f6c3a469330be309eaad627
SHA256 73c41e29e75e998a186e6fc74b81fbc537f3b232a5d07b5621e8fd3485506b87
SHA256 06cc1531e8f912ca9e5f1e37f442d2145df6b8cdadf3d1d7abfc9dfae6bb98ab
SHA256 6d74cb6e7e93277cef4a8d62fad53d806be140aaddb89b44d9b7eb8307c5b7f5
SHA256 04e561cf760209b3bef678117366dd184f4474e4ba15ec9b95cddea4e01ade95
SHA256 6314ba359b26e05fba095ac58e3f9451243081cbc331bf60522ad69439b438c4
SHA256 2f45d682260ca936e1c577c845576eef009a7017882ed57b6a8b76f9f6b83ad6
SHA256 cc1afcf52046e08ba1314e74a852eec27211395c77f5b911de52245fae93ab3d
SHA256 97b13680d6c6e5d8fff655fe99700486cbdd097cfa9250a066d247609f85b9b9
SHA256 281d72fe63fae2e3b1b74c3953b3b4c429948d1f56c7897104754393dc0ab38f
SHA256 e2790ea81b297f0b10871b9a16d0adbb670c7ea5900d64bc1d2f65a296d87ade
SHA256 a9e663aa23a75f8574b5e10b4bea1deed22b49ed6dc451e4bb45f217811978a0
SHA256 caac78ebfdb6102c05b82a00cf1acda1797cf4dc1bcc66336286289c8a309b47
SHA256 bb85dedadd0b96084eb6c45b4a7650e33aa149f286d1272f17c56228278fe5b8
SHA256 abffa851076dd0f2d408e66d047a2d50415513a17239b2d2ece33891c9c0ad23
SHA256 9cfd1878606c41624b2e41a96eefcab6ca673d07f8e8f98ce6e86c4c8a806f5e
SHA256 3cc5d88b8a69dec6a606aa01c29789811442b2572dcc51e25aa7711e657b51f3
SHA256 e6ec5b942625bc910b3dc1c8f28940d5e5ba4f5fb89c7c189c61c3b46945f1f1
SHA256 b37f2e7dd94e441a129629d1d352b82bb4a0e9b98a1c9a188f95e6c148e6b407
SHA256 78b7b0eddc1d05cafd0202729f488daa027cac375dcd688c10fae34f65e0224e
SHA256 9b4f6d76d125524f7ac11ddc3251152ca45c79d44a4359e831ebe0ec3142b609
SHA256 5e945c1d27c9ad77a2b63ae10af46aee7d29a6a43605a9bfbf35cebbcff184d8
SHA256 2d79bf996a3f5a10f5b42c6449df14a00395390f5028dca18aa768651ed7bf62
SHA256 e8cbcdac6f39abf67c9c297203312d39f83a150277e0672a83657d38e6ef5446
SHA256 e25d15f721362c6e6110ce21c3ced554a2c8510a6c5627457688fdb397608656
SHA256 c8a7a0a8d702ce8087617a12572c00eefb92508ea6f1cfd95fe14c26107cef67
SHA256 3f8437665c6c7638e5f86d034ac2ce3367ab97533c45476e6beee8863c365ff6
SHA256 1a35563989c5528348713b0246374bb3c8d316561dc6b9bf17f2b20c88fbd178
SHA256 69afcd4b38bf84069c4f520e65ef7df31411d69819d88716cbb5e17178e5b5b0
SHA256 aef677a0a83d1ab1036fde6926e848674d7d53bf5dc3bd984c6c6d51337c4b61
SHA256 76499405dd3cea63f170813d88ab32b2716e5682b8083a94966d494b706eadc7
SHA256 acee75cd346795ceb02fc30aa822d13c4132e64fd36b5244dd822199a5a0c0a7
SHA256 4f2ae18fe003ec4dfd47255f24141b42af1b423c94a1abcbe8af337f251c8789
SHA256 3540b0720b610f93713df454af8ad1e7bd0e0eb3099d115a8cc5a9b7a85d3c50
SHA256 e95cde1e6fa2ce300bf778f3e9f17dfc6a3e499cb0081070ef5d3d15507f367b
SHA256 8c6e41a5e33749c31516b1931e129bbdaeff7f3434c4259c8842b0b9f047b6b7
SHA256 47b27cb727b1ada6c65c7bf30b57537b26080f1f5a6730be91b767427945d731
SHA256 658e17adf469ec61f1cc62a0c3932185e94f9557597dcf4714575706efd71141